# Kenny Clamp, exposed



## MDShunk (Jan 7, 2007)

Here's the front and back of the white paper that comes in the package (installation instructions):


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## JohnJ0906 (Jan 22, 2007)

I like the instructions for connecting it to a raceway. Connector-rigid coupling-reducer- kenny clamp :whistling2:


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## brian john (Mar 11, 2007)

My question was there ever proff there is a need for this connector?????


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## macmikeman (Jan 23, 2007)

Things pass hands unnoticed. Friendships get made. Requirement codes get submitted and passed. Devices become either mandatory, or sometimes the previously good ways of doing something get shut down. I'm not saying anything at all here about this particular device in question, but I bet that within 10 years it is either required, or else using a romex clamp or going into a box with no "listed protective device" will become outlawed. Its called Capitalism. This device is just one more thing I will have to stock, but it don't look so bad to me. At least it don't look like something that will cause call backs like AFCI breakers sometimes do. Carry on matey's.:thumbup:


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## frenchelectrican (Mar 15, 2007)

Md.,, That kenny clamp look little diffrent than what i did see that one look heck alot better than what i got but one question with the Kenny clamp is that all brass construction ??


Thanks , Marc


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## JohnJ0906 (Jan 22, 2007)

I believe it's all brass, except the locknut.


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## MDShunk (Jan 7, 2007)

brian john said:


> My question was there ever proff there is a need for this connector?????


Not that I am aware of. I think it just looks cool. :thumbsup:

Yeah, it's all brass, except the locknut. It's quite the chunk.


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## brian john (Mar 11, 2007)

Lets invent something that has no basis for need or use and then market it and make it's use mandatory as is happening in some jurisdictions (I HAVE BEEN TOLD no solid evidence of this).


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## JohnJ0906 (Jan 22, 2007)

Required in Prince Georges county, MD (at least I'm told)

This was invented by a..... PG county inspector!:laughing:


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## MDShunk (Jan 7, 2007)

JohnJ0906 said:


> Required in Prince Georges county, MD (at least I'm told)
> 
> This was invented by a..... PG county inspector!:laughing:


That's exactly the story I heard. Matter of fact, the little shelf tag next to the bin of Kenny Clamps says "required in Maryland now".  I'm just over the border from Maryland, so I guess there must be some contractors here that work down there. I never really saw the point. Maryland is a licensing nightmare.


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## JohnJ0906 (Jan 22, 2007)

I've never seen them required for residential. I used them with a past employer who did commercial. He got red-tagged one time, and just started using them on every service "to be sure".

I do like them, I think it makes a clean install, but I've never been failed for not using them.

Licencing nightmare? No! Just because every single county is different, different licenses, different amendments, etc...


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## MDShunk (Jan 7, 2007)

JohnJ0906 said:


> Licencing nightmare? No! Just because every single county is different, different licenses, different amendments, etc...


That's what I mean. PA has lots of licenses for every town you go to, but at least everyone's on the same NEC, without amendments. One of my licenses used to reciprocate in Washington County, MD, but they stopped that a few years back. I really don't want to drive more than maybe 20 miinutes to get the the next job anyhow. I got a call to go to Fredrick, MD a few weeks ago. Major red flag right there, because there must be 100 EC's they could have called within their local area. Not only am I not licensed there, I don't have an MHIC number anymore, even if I wanted to go there for whatever reason. John, I think you can have Maryland! If you open up shop one day, I'll give you all my Maryland calls. Maybe 2 or 3 a year. :laughing:


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## JohnJ0906 (Jan 22, 2007)

Its all good! :laughing: 

I had a friend who moved to PA a few years ago, and I couldn't believe the liquor laws up there! Crazy! :laughing: 
'Course, that was when I drank...:whistling2:


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## MDShunk (Jan 7, 2007)

JohnJ0906 said:


> I had a friend who moved to PA a few years ago, and I couldn't believe the liquor laws up there! Crazy!


Yeah, you'd have to put some real effort into becoming a drunken alcoholic in PA.


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## JohnJ0906 (Jan 22, 2007)

MDShunk said:


> Yeah, you'd have to put some real effort into becoming a drunken alcoholic in PA.


There have always been some things in life I have been willing to work for!!:laughing:


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## Magnettica (Jan 23, 2007)

I did a service the other day. Used them for the first time. Not bad. The 2 little pieces cut in half were a pain to get back into place to secure the wire, but after that they were fine (except for the broken locknut that came with it).

There's really no need for these though, plastic button connector are still fine.


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## MDShunk (Jan 7, 2007)

Magnettica said:


> (except for the broken locknut that came with it).


Really? That sorta surprises me. Every one I have used has had an exceptionally high-quality locknut. 

On a related note, I got a batch of "Topaz" brand 3/4" EMT connectors that were absolute junk. Every single locknut would break the second you tried to tighten it up. You could take the locknut in the palm of you hand and crush it. It was the weirdest thing.


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## Magnettica (Jan 23, 2007)

Yeah... for whatever reason, the locknut wouldn't tighten and / or the threads didn't line up. I just used another locknut.

Question: would using another locknut be a violation of 110.3 (B)?

Technically, I would say yes.


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## MDShunk (Jan 7, 2007)

Magnettica said:


> Question: would using another locknut be a violation of 110.3 (B)?
> 
> Technically, I would say yes.


:laughing: Don't sweat it! I don't think there's a single inspector, living or dead, that would fault you for getting another handy locknut if you had a bum one or a missing one.


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## Bob Wire (Aug 7, 2010)

*kenny clamp*

Evidently no one's pointed out the current that a grounding electrode can have. Lost neutral, load imbalance. The chock effect can happen when these condition's occur, that's one of the reasons the kenny clamp was listed and approved for the application. No, a plastic bushing won't provide the necessary safety and won't comply with 250.8 of the NEC. Furthermore UL 67 the standard for panelboards only list a residential bond screw at 30 amperes. The kenny clamp is tested to 2000 amperes. The standard for panelboards is UL 467 requires this test. Also 2011 NEC, 250.8 list the grounding electrode conductor to have a listed fittings, so you nonlisted installers beware. Get up to date and become code compliant. There's no where in Maryland that requires a specific requirement for kenny clamp only the NEC, 250.8, 300.15 and 110.3(B). I use them on a daily bases, great installation for separately derived systems. The kenny clamp bonds the transformer can to XO and eliminates the need for an additional lug up to 300 KVA, where the equipment bonding jumper becomes larger than grounding electrode conductor. ok lets have fun


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## Bob Badger (Apr 19, 2009)

Bob Wire said:


> Evidently no one's pointed out the current that a grounding electrode can have. Lost neutral, load imbalance. The chock effect can happen when these condition's occur, that's one of the reasons the kenny clamp was listed and approved for the application. No, a plastic bushing won't provide the necessary safety and won't comply with 250.8 of the NEC. Furthermore UL 67 the standard for panelboards only list a residential bond screw at 30 amperes. The kenny clamp is tested to 2000 amperes. The standard for panelboards is UL 467 requires this test. Also 2011 NEC, 250.8 list the grounding electrode conductor to have a listed fittings, so you nonlisted installers beware. Get up to date and become code compliant. There's no where in Maryland that requires a specific requirement for kenny clamp only the NEC, 250.8, 300.15 and 110.3(B). I use them on a daily bases, great installation for separately derived systems. The kenny clamp bonds the transformer can to XO and eliminates the need for an additional lug up to 300 KVA, where the equipment bonding jumper becomes larger than grounding electrode conductor. ok lets have fun


There is no code requirement to use one at all.

It is much about nothing.


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## Speedy Petey (Jan 10, 2007)

Bob Wire, you seem to know what you are talking about. Why not post an introduction here: http://www.electriciantalk.com/f3/


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## crosport (Apr 4, 2010)

Technically here in Canada the first point at which the main ground should bond is at the neutral terminal.Using that connector would violate that code rule.I usually wrap a little green tape around the bare conductor where it goes thru the 2 screw connector I typically use,just to isolate it from the can.


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## nrp3 (Jan 24, 2009)

_What is this chock effect? I still don't see what the need is. Whats wrong with the 3/8 or so inch holes they provide us on residential panels? Bonding issue? I guess if the mains fall out and land on the can. Listed fittings, or listed for terminating a grounding conductor in a panel? I don't take the updates till the beginning of the year._


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## kbsparky (Sep 20, 2007)

Bob Wire said:


> ...There's no where in Maryland that requires a specific requirement for kenny clamp ....


I heard that PG county was requiring these? Anyone from there care to comment? Do they carry `em at Rexel, Graybar, or Maurice?


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## manchestersparky (Mar 25, 2007)

PG county does require the use of the Kenny Clamp.

But then of course the person who created the clamp is a PG county inspector. He named the clamp after his son.


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## Speedy Petey (Jan 10, 2007)

manchestersparky said:


> PG county does require the use of the Kenny Clamp.
> 
> But then of course the person who created the clamp is a PG county inspector. He named the clamp after his son.


And no one has a problem with this? :001_huh:


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## RIVETER (Sep 26, 2009)

This is an old thread. Is the Kenny clamp catching on in 2010? I've never heard of them.


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## 480sparky (Sep 20, 2007)

RIVETER said:


> ............ I've never heard of them.



Click here.


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## 480sparky (Sep 20, 2007)

Bob Wire said:


> ......... Also 2011 NEC, 250.8 list the grounding electrode conductor to have a listed fittings, so you nonlisted installers beware. ..........


What about a ¼" hole?


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## RIVETER (Sep 26, 2009)

480sparky said:


> Click here.


Thanks for the link but I still don't see why it is better than a pvc sleeve in the application on the link...and a lot cheaper. But thanks, I am saving the link.


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## brian john (Mar 11, 2007)

I wonder if the OP's son is named KENNY?:laughing::laughing::laughing::laughing:

In all the transformer faults and downstream faults I have investigated I can truly saw I saw no evidence that a kenny clamp would have been any more effective that a NM connector.

Lots of ways to make this connection without a kenny clamp.

And not against using them BUT saying this one device is mandatory (as some noted) is IMO wrong too many other ways to complete the connection.


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## brian john (Mar 11, 2007)

Bob Wire said:


> Evidently no one's pointed out the current that a grounding electrode can have. Lost neutral, load imbalance.


Load imbalance HOW is that resulting in ground current?



> No, a plastic bushing won't provide the necessary safety[/
> 
> quote]
> 
> ...


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## Bob Badger (Apr 19, 2009)

brian john said:


> I wonder if the OP's son is named KENNY?:laughing::laughing::laughing::laughing:
> 
> In all the transformer faults and downstream faults I have investigated I can truly saw I saw no evidence that a kenny clamp would have been any more effective that a NM connector.


When running a bare copper ground as the Kenny clamp is made for there is no NEC requirement to even use a connector, as Ken pointed out a 1/4" hole is all you need.


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## 480sparky (Sep 20, 2007)

The entire 'Kenny Clamp is Required' fiasco is interesting.

If Southwire and Carlon put out an set of instructions about THHN and PVC conduit being 'listed for use in dwellings', would inspectors suddenly demand that all dwellings be wired with PVC and THHN?


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## manchestersparky (Mar 25, 2007)

Speedy Petey said:


> And no one has a problem with this? :001_huh:


NO. He has a UL listing and a ton of engineering reports on how they are better then just using the old fashioned 2 screw metal romex connector.

He goes to trade shows everywhere pushing them too. 
They tried real hard to get the jurisdiction I work for to require them, but until it's in the NEC that will not happen. We try to minimze our admendments to the code and keep it simple.


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## Bob Wire (Aug 7, 2010)

Well Badger, everyday we lose a 30 ampere rated main bond screw in residential panelboards. Majority of the time the loss of the panelboard is misinterpreted. Today"s power grids are stress due to old load demand calculations. Faults and surges can easily exceed 30 amperes and damage the main bond screw. Residential panelboards are not required to be tested, see UL 67. The kenny clamp will save the panelboard when these conditions occur. Now the State of Florida looses the grounding electrode conductor due to lighting almost on a daily bases, this is due to the choke effect. When current is traveling on the panelboard frame, due to fault or surge or lighting and encounters a grounding electrode conductor installed in a weep hole or in a drilled hole without a listed fitting the grounding electrode conductor can burn off at the entry point into the panelboard. The event is even worse when the conductor is insulated. This is called the choke effect. Recently in Alexandria, Virginia a AC unit faulted and took out the main bonding screw in the panelboard the fault taking the next available path, burnt the building down. Times change as well as the electrical industry, old ways and applications give to new ways and better applications, keep up the good work.:no:


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## Speedy Petey (Jan 10, 2007)

Bob Wire, what affiliation do you have with the Kenny Clamp?


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## macmikeman (Jan 23, 2007)

Bob Wire said:


> Well Badger, everyday we lose a 30 ampere rated main bond screw in residential panelboards. Majority of the time the loss of the panelboard is misinterpreted. Today"s power grids are stress due to old load demand calculations. Faults and surges can easily exceed 30 amperes and damage the main bond screw. Residential panelboards are not required to be tested, see UL 67. The kenny clamp will save the panelboard when these conditions occur. Now the State of Florida looses the grounding electrode conductor due to lighting almost on a daily bases, this is due to the choke effect. When current is traveling on the panelboard frame, due to fault or surge or lighting and encounters a grounding electrode conductor installed in a weep hole or in a drilled hole without a listed fitting the grounding electrode conductor can burn off at the entry point into the panelboard. The event is even worse when the conductor is insulated. This is called the choke effect. Recently in Alexandria, Virginia a AC unit faulted and took out the main bonding screw in the panelboard the fault taking the next available path, burnt the building down. Times change as well as the electrical industry, old ways and applications give to new ways and better applications, keep up the good work.:no:


This belongs on the mega-vitamin and hair loss cure section of the forum


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## Bob Badger (Apr 19, 2009)

Bob Wire said:


> everyday we lose a 30 ampere rated main bond screw in residential panelboards.





> Majority of the time the loss of the panelboard is misinterpreted.





> Today"s power grids are stress due to old load demand calculations. Faults and surges can easily exceed 30 amperes and damage the main bond screw.





> Now the State of Florida looses the grounding electrode conductor due to lighting almost on a daily bases, this is due to the choke effect.





> When current is traveling on the panelboard frame, due to fault or surge or lighting and encounters a grounding electrode conductor installed in a weep hole or in a drilled hole without a listed fitting the grounding electrode conductor can burn off at the entry point into the panelboard.



Can you provide unbiased documentation for any of the above 5 statements or should we just take your word for it?




> Recently in Alexandria, Virginia a AC unit faulted and took out the main bonding screw in the panelboard the fault taking the next available path, burnt the building down.


And the Kenny Clamp would have helped how? 





> Times change as well as the electrical industry, old ways and applications give to new ways and better applications, keep up the good work.:no:


There is nothing new here, same old smoke and mirrors trying to sell a product by scaring people into believing that they need this particular product or bad things will happen.


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## oldtimer (Jun 10, 2010)

macmikeman said:


> This belongs on the mega-vitamin and hair loss cure section of the forum


 We have a hair loss section?????? :laughing::laughing::laughing:SIGN me up QUICK. OOPS! Too late!!!


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## 480sparky (Sep 20, 2007)

oldtimer said:


> We have a hair loss section?????? :laughing::laughing::laughing:SIGN me up QUICK. OOPS! Too late!!!



What is 'hair' ?


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## oldtimer (Jun 10, 2010)

480sparky said:


> What is 'hair' ?


 Actually, I was told you can't have HAIR, and BRAINS too. :laughing::laughing:


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## Bob Wire (Aug 7, 2010)

Check with an electrical engineer on the chock effect, I was told to use them for my installations, don't really have a biased opinion one way or the other, but encounter many panelboards with lost bond screws resulting in fires. These occurrences are documented in the local jurisdictions through fire damage reports. Not a collector, but the next time I'll get a copy to post. I was informed by an electrical inspector in the City of Alexandria over the fire issue. Florida issues are a known fact, talk with any electrical inspector over the lighting issue. The kenny clamp actually works as a main bonding jumper and is listed for the application, UL white book, I just have an open mind, with 45 years of electrical experience and fire and electrical investigations under my belt. But I don't believe in the term expert so I'll refrain from that interpretation. CMP 5's interpretation of 250.8 using listed fitting encompasses the term grounding conductor, see 800.100. This issue is resolved in the 2011 NEC and was defined in the 2005 ROP response. FYI, just a student of the code and like to keep an open mind.


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## Speedy Petey (Jan 10, 2007)

Bob Wire said:


> ......, but encounter many panelboards with lost bond screws resulting in fires. These occurrences are documented in the local jurisdictions through fire damage reports.


Well, I am just a kid with a mere 25 years experience, but I have NEVER seen nor heard of this happening. Maybe I am hanging out with the wrong crowd.


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## jwjrw (Jan 14, 2010)

These occurrences are documented in the local jurisdictions through fire damage reports.




They always blame the electrical if they cant figure out what started the fire.


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## 480sparky (Sep 20, 2007)

Fires due to lost bonding screws. Hmmm. Seems to be right up there with 'athletes foot' and 'halitosis'......


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## I_get_shocked (Apr 6, 2009)

Can someone post a picture of a panel with a lost (burnt???) bonding screw? I cant seem to find one and have never come across such a situation.


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## MDShunk (Jan 7, 2007)

I_get_shocked said:


> Can someone post a picture of a panel with a lost (burnt???) bonding screw? I cant seem to find one and have never come across such a situation.


I've seen a lot of stuff, but that's one thing I've never seen. I might guess that if a bond screw was burnt off, it may not have been properly installed in the first place. What about the other end of the wire? What about burned off GEC's in water pipe clamp screws? Yeah, you're right. That never happens either... at least not that I've ever seen.


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## macmikeman (Jan 23, 2007)

Here is a picture of a panel that burned due to a lack of kenny clamp.









And another. Just a 50 cent clamp would have saved 50 Cent's house....









This picture is the proof though that it is a big time hazard to not use a kenny clamp.


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## jwjrw (Jan 14, 2010)

macmikeman said:


> Here is a picture of a panel that burned due to a lack of kenny clamp.
> 
> And another. Just a 50 cent clamp would have saved 50 Cent's house....
> 
> ...


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## MDShunk (Jan 7, 2007)

If the Kenny Clamp was only 50 cents, I'd be more likely to use them. They're about 6 bucks.


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## macmikeman (Jan 23, 2007)

MDShunk said:


> If the Kenny Clamp was only 50 cents, I'd be more likely to use them. They're about 6 bucks.


True, but I couldn't figure out how to mix that in with 50 Cents house fire....


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## nrp3 (Jan 24, 2009)

This is not to say that things can't be improved, but if it was such a rampant problem, I would think UL would have caught on long ago. Manufacturers would have changed etc... I buy in to AFCIs more than this item. I haven't heard much evidence to support it. When I get to code update in January, if Joe Ross is still giving it, I'll ask about it.


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## macmikeman (Jan 23, 2007)

This reminds me of another forum. There was a guy who showed up about every other day for at least two years annoying all with insisting that each and every electrical termination made must be first wirebrushed and then coated with anti-ox, regardless of aluminum or copper. :whistling2:


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## Bob Badger (Apr 19, 2009)

macmikeman said:


> This reminds me of another forum. There was a guy who showed up about every other day for at least two years annoying all with insisting that each and every electrical termination made must be first wirebrushed and then coated with anti-ox, regardless of aluminum or copper. :whistling2:


Not just wire brushed, I think it was garnet paper or some other fairly odd item.


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## CFL (Jan 28, 2009)

Bob Wire said:


> Well Badger, everyday we lose a 30 ampere rated main bond screw in residential panelboards. Majority of the time the loss of the panelboard is misinterpreted. Today"s power grids are stress due to old load demand calculations. Faults and surges can easily exceed 30 amperes and damage the main bond screw. Residential panelboards are not required to be tested, see UL 67. The kenny clamp will save the panelboard when these conditions occur. Now the State of Florida looses the grounding electrode conductor due to lighting almost on a daily bases, this is due to the choke effect. When current is traveling on the panelboard frame, due to fault or surge or lighting and encounters a grounding electrode conductor installed in a weep hole or in a drilled hole without a listed fitting the grounding electrode conductor can burn off at the entry point into the panelboard. The event is even worse when the conductor is insulated. This is called the choke effect. Recently in Alexandria, Virginia a AC unit faulted and took out the main bonding screw in the panelboard the fault taking the next available path, burnt the building down. Times change as well as the electrical industry, old ways and applications give to new ways and better applications, keep up the good work.:no:


I live and work in Florida and have installed hundreds of meter based surge arrestors for the POCO. Many of the buildings had suffered lightning damage and I can only recall seeing similar damage to what you speak of a couple of times. I wouldn't mind trying the device for use on a sds to simplify things, although you still would need to install lugs for your egc's.


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## brian john (Mar 11, 2007)

Bob Badger said:


> When running a bare copper ground as the Kenny clamp is made for there is no NEC requirement to even use a connector, as Ken pointed out a 1/4" hole is all you need.


Which is about how 95% of the ones I see are installed.


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## Magnettica (Jan 23, 2007)

LOL Macmikeman!

I've used the Kenny clamps one time a few years ago and that's it.


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## Lone Crapshooter (Nov 8, 2008)

I understand the CHOKE EFFECT not the CHALK EFFECT. It is the reason that parallel services and feeders you intermix phases and also why you always run 2 wires through conduit and why you must bond both ends of a ferris alloy conduit (rigid or EMT)when you run a single grounding conductor through the conduit. In industrial work allot of times you will see individual conductors dropping out of cable tray feeding switchgear or motor control centers.
If you look where these conductors penetrate the metal enclose there is ether a piece of plastic or aluminum this cancels the CHOKE EFFECT.

With that being said I can see that the Kinney Clamp MIGHT be beneficial but overall I think it is much a do about nothing.


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## brian john (Mar 11, 2007)

Lone Crapshooter said:


> With that being said I can see that the Kinney Clamp MIGHT be beneficial but overall I think it is much a do about nothing.


My issue is that it is required and supposedly alternative methods that are just as effective are not permitted. 

If mandatory use of this clamp is all that is allowed then there are issues with this requirement.


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## Bob Wire (Aug 7, 2010)

*kenny clamp*

Choke effect is not canceled by the plastic bushing. I'll just keep installing them in accordance with applicable codes I feel that are applicable. Let your conscience be your guide, it you trust a 30 ampere main bonding screw and you believe there is no need or fault current can't take out a nonlisted fitting, keep installing the way you have always done. I'm a proponent for safety and feel it's a better connection, complies with the standard and listing and labeling, also 300.15. If your happy with a romex connector go for it. :no:


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## jwjrw (Jan 14, 2010)

Bob Wire said:


> Choke effect is not canceled by the plastic bushing. I'll just keep installing them in accordance with applicable codes I feel that are applicable. Let your conscience be your guide, it you trust a 30 ampere main bonding screw and you believe there is no need or fault current can't take out a nonlisted fitting, keep installing the way you have always done. I'm a proponent for safety and feel it's a better connection, complies with the standard and listing and labeling, also 300.15. If your happy with a romex connector go for it. :no:


 


 :no: :laughing:
Sorry I just had to laugh at this.......


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## brian john (Mar 11, 2007)

Bob Wire said:


> Choke effect is not canceled by the plastic bushing. I'll just keep installing them in accordance with applicable codes I feel that are applicable. Let your conscience be your guide, it you trust a 30 ampere main bonding screw and you believe there is no need or fault current can't take out a nonlisted fitting, keep installing the way you have always done. I'm a proponent for safety and feel it's a better connection, complies with the standard and listing and labeling, also 300.15. If your happy with a romex connector go for it. :no:


You assume a romex connector, DO YOU KNOW WHAT HAPPENS WHEN YOU ASSUME.

You can make up your own codes all you want THIS CLAMP IS NOT MANDATORY there are methods that work just as well.

And I do not rely on a 30 amp screw.

You would have had a more intelligent, less in your face discussion had you not come in here with your first post with a holier than though attitude. You might be the KING of ELECTRICITY to the trade but there are some here as knowledgable as you (while maybe not quite as know it all but close?). SO tone your attitude down and have a polite discussion and I bet many of the electricians would be buying the product you surely have a vested interest in.


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## 480sparky (Sep 20, 2007)

Bob Wire said:


> .........I'll just keep installing them in accordance with applicable codes I feel that are applicable.


If you don't feel they're applicable, you'll just ignore them then?



Bob Wire said:


> Let your conscience be your guide, it you trust a 30 ampere main bonding screw and you believe there is no need or fault current can't take out a nonlisted fitting, keep installing the way you have always done.


OK, so let's say 31 amps makes it through the bonding screw. Now where does it go?



Bob Wire said:


> I'm a proponent for safety and feel it's a better connection, complies with the standard and listing and labeling, also 300.15.


I feel just fine using the connection at the neutral bar.



Bob Wire said:


> If your happy with a romex connector go for it. :no:


Screw using an NM connector. I use a _really_ high-tech solution.......... a ¼" drill bit.


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## brian john (Mar 11, 2007)

Lone Crapshooter said:


> It is the reason that parallel services and feeders you intermix phases and also why you always run 2 wires through conduit


That's inductance resulting in heating not a chock.



> and why you must bond both ends of a ferris alloy conduit (rigid or EMT)when you run a single grounding conductor through the conduit.


Reportedly there is a 60% current on the conduit and 40% on the conductor.



> In industrial work allot of times you will see individual conductors dropping out of cable tray feeding switchgear or motor control centers.
> If you look where these conductors penetrate the metal enclose there is ether a piece of plastic or aluminum this cancels the CHOKE EFFECT.


A single opening bushed with plastic, non-ferrous metal, a single opening or slots between the openings.



> With that being said I can see that the Kinney Clamp MIGHT be beneficial but overall I think it is much a do about nothing.


I agree


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## Lone Crapshooter (Nov 8, 2008)

Perhaps I should have said that they cut a large square out of the top of the gear and replace it with a plastic or aluminum sheet . This prevents magnetic paths from developing that results in inductive heating.
Does not a choke or line reactor work on induction and magnetic fields
just like a transformer or motor?


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## Bob Wire (Aug 7, 2010)

Thanks for the brow beating. I've never been wholer than now, nice to know I appear that way. Whats so great about the electrical trade is there are many applications and methods for installation. I was just pointing out what I though was the obvious. I like the easy and most labor saving methods. I like the connector it answers many questions in my mind, there's a lot of applicable code to go along with installing the kenny clamp, not to mention the strain relief benefit. If you hate them, fine don't use them. I believe its better than a 30 ampere bond screw, its rated for a 2000 amperes load test under UL 486 standards. I feel more comfortable installing and maintain by main bonding jumper in those residential applications. If your comfortable with a lug, terminal bar or a bond bushing go for it. I believe that a 1/4 hole does not meet the 250.8 requirement especially without a fitting (close all opening). I was just pointing out 250.8 requirement for listed grounding and bonding fittings, take it or leave, its not changing my life, just a great code discussion. Have a great day.


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## 480sparky (Sep 20, 2007)

OK, you keep talking about a more-than-30-ampere current.

_From where_?


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## Bob Badger (Apr 19, 2009)

Bob Wire said:


> Thanks for the brow beating.


No problem, we are glad to help.

Now I must have missed it but could you come clean and tell us how you are connected to the sales of this fitting?





> I believe that a 1/4 hole does not meet the 250.8 requirement especially without a fitting (close all opening).


1) The NEC does not require a fitting of any kind at all where a bare GEC enters an enclosure.

2) The NEC only requires that this bare GEC to be bonded by listed connector to the service ONCE and that one time will be made with a listed connector at the neutral or grounding bus. 




> I was just pointing out 250.8 requirement for listed grounding and bonding fittings


Yes and we are all very familiar with 250.8, it does not require the use of a Kenny clamp.




> take it or leave, its not changing my life, just a great code discussion.


Not even a great code discussion, just a blatant sales pitch.


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## Bkessler (Feb 14, 2007)

MDShunk said:


> I've seen a lot of stuff, but that's one thing I've never seen. I might guess that if a bond screw was burnt off, it may not have been properly installed in the first place. What about the other end of the wire? What about burned off GEC's in water pipe clamp screws? Yeah, you're right. That never happens either... at least not that I've ever seen.


I was at a panel once that had a direct short on a plug a HO installed, BUT when you turned on the breaker thier was a huge spark at the water bond and the breaker would shut off. I didn't do any work there though, I .........was to expensive.


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## macmikeman (Jan 23, 2007)

Bob Wire said:


> I believe that a 1/4 hole does not meet the 250.8 requirement especially without a fitting (close all opening). I was just pointing out 250.8 requirement for listed grounding and bonding fittings, take it or leave, its not changing my life, just a great code discussion. Have a great day.


You are entitled to your beliefs as all the other posters on this thread. Doesn't make you right however. But here is something else to invent and then push into the code book. Just about every panel I ever saw had larger than 1/4 openings where the screw mounting holes are. Also the corners where the sheet metal folds over onto itself usually have an opening there as well. But all will be safe and sound once you come up with the new UL listed and tested "Panel Apron" which will fit over all panels and kenny clamps and then provide protection from all manner of 30 amp bonding screws shooting sparks out thru those holes. Make sure you cut me in for my 20% of the take on this item...


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## jbrookers (Dec 7, 2008)

If this is such a big problem, why not fix the ground bars and bonding screws? Why bond in two places in the panel?


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## brian john (Mar 11, 2007)

Bob Wire said:


> Thanks for the brow beating. I've never been wholer than now, nice to know I appear that way. .



Heck you got off easy more than one person has called me an asshole or was that a flaming asshole, on more than one occasion. And I am no a-hole, I am a saint, sort of a god to electricity, just ask me.

Think of this, most people do not like change, GFCI's, AFCI's for example. Plus we like to think the way we have always done is perfectly OK otherwise, we have been screwing up for a long time and few craftsmen want to think about that.


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## Jeff000 (Jun 18, 2008)

crosport said:


> Technically here in Canada the first point at which the main ground should bond is at the neutral terminal.Using that connector would violate that code rule.I usually wrap a little green tape around the bare conductor where it goes thru the 2 screw connector I typically use,just to isolate it from the can.


Yes. Should be bonded at the first point of disconnect. Not multiple locations. 





Bob Wire said:


> Well Badger, everyday we lose a 30 ampere rated main bond screw in residential panelboards. Majority of the time the loss of the panelboard is misinterpreted. Today"s power grids are stress due to old load demand calculations. Faults and surges can easily exceed 30 amperes and damage the main bond screw. Residential panelboards are not required to be tested, see UL 67. The kenny clamp will save the panelboard when these conditions occur. Now the State of Florida looses the grounding electrode conductor due to lighting almost on a daily bases, this is due to the choke effect. When current is traveling on the panelboard frame, due to fault or surge or lighting and encounters a grounding electrode conductor installed in a weep hole or in a drilled hole without a listed fitting the grounding electrode conductor can burn off at the entry point into the panelboard. The event is even worse when the conductor is insulated. This is called the choke effect. Recently in Alexandria, Virginia a AC unit faulted and took out the main bonding screw in the panelboard the fault taking the next available path, burnt the building down. Times change as well as the electrical industry, old ways and applications give to new ways and better applications, keep up the good work.:no:


I've seen a house panel that was hit by lighting, did a number on the panel, and warped the mast where it hit. But the #8 ground wire held up just fine, and the house didn't burn to the ground. 
I've never seen a bonding screw "taken out" by a fault. Not one that was correctly installed. I'm not even sure I understand how this silly clamp would do anything if the bonding screw was taken out.


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## brian john (Mar 11, 2007)

Jeff000 said:


> Yes. Should be bonded at the first point of disconnect. Not multiple locations.
> 
> 
> 
> ...


The concept is that by not bonding at the entry point to the back box or transformer you set up a choke effect on the grounding electrode conductor at the entry point. The EGC will not carry all the fault current.


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## Jeff000 (Jun 18, 2008)

brian john said:


> The concept is that by not bonding at the entry point to the back box or transformer you set up a choke effect on the grounding electrode conductor at the entry point. The EGC will not carry all the fault current.


Interesting, I have never heard the term choke effect before. I will have to look into it more to have an opinion really. But as or right now I dunno....


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## brian john (Mar 11, 2007)

Jeff000 said:


> Interesting, I have never heard the term choke effect before. I will have to look into it more to have an opinion really. But as or right now I dunno....


I am going to test this, I am sure I can pass 7,500-10,000 amps through a short 
#2 solid.

Test
No Kenny clamp
Kenny Clamp
#2 bonded outside can
#2 bonded inside can


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## frenchelectrican (Mar 15, 2007)

brian john said:


> I am going to test this, I am sure I can pass 7,500-10,000 amps through a short
> #2 solid.
> 
> Test
> ...


If you can do that test can ya post the photo to show the details ??

Merci.
Marc


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## oldtimer (Jun 10, 2010)

Jeff000 said:


> Interesting, I have never heard the term choke effect before. I will have to look into it more to have an opinion really. But as or right now I dunno....


 Me Too! I would like an explanation of the term (choke effect).

Is it sometimes referred another way?


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## Mr. Sparkle (Jan 27, 2009)

frenchelectrican said:


> If you can do that test can ya post the photo to show the details ??
> 
> Merci.
> Marc


Photo......we want video dammit!


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## brian john (Mar 11, 2007)

Bob Wire we seemed to have gotten on even ground with you BUT there are a few questions posed in this thread that you have yet to answer?


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## renosteinke (May 14, 2009)

Sorry to resurrect this ancient thread, but ... a few folks asked "What is this 'choke effect' that others mention?" I thought I'd try to explain it in simple terms.

When electrical current flows, you have a magnetic field created around the wire. The opposite is also true: pass a wire through a magnetic field, and current will flow.

We see this effect all the time; motors, generators, transformers, and clamp meters all take advantage of this effect to work.

If the metal affected is magnetic, the magnetic field can be converted directly into heat energy, rather than electrical energy. How much heat is made depends lagely on the frequency of alternating current, and to a lesser extent on the amount of current. (Which, btw, explains why there are no DC transformers).

With the magnetic field creating heat in the metal, the amount of current flowing through the wire is reduced. This is the "choke" effect.

Mike Holt came up with a neat demonstration of the choke effect. Imagine you have 500-ft. of #14 wire. How much current would a dead short draw?
Well, if you look to the resistance tables and do the math, you get an answer somewhat under 100 amps. Yet, you can take a common spool of #14, hook up a "hot" to one end and a neutral to the other and ... surprise! ... you'll draw only about 12 amps. You'll also hear a lot of buzzing and see the spool jumping around some. The current is restricted by the magnetic field interfering with itself, as the wire coils about itself.

When we have multiple wires in a conduit, the different magnetic fields of various wires tend to cancel each other out. 

The "Kenny Clamp" will prevent both induction heating and interfering magnetic fields by bonding the ground wire to the steel can as it passes through it.

Is this a real problem? Would the fault current in a #4 copper wire be affected enough to keep breakers from tripping? For your typical residential service, at only 60 Hertz, I doubt it. Any contact - be it from using a two-screw clamp or just casual contact with the can as the wire exits that 1/4" hole - would be enough of a connection to prevent a magnetic field from forming in the can.

Industrial uses might be another story - between having 3-phase service, harmonics, and much higher currents, you just might induce a strong enough field to cause trouble.

Using a plastic bushing, as one suggested, is the opposite of what you want. Insulating the opening will only prevent that incidental bonding as the wire passes through.


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## Mshea (Jan 17, 2011)

renosteinke said:


> Sorry to resurrect this ancient thread, but ... a few folks asked "What is this 'choke effect' that others mention?" I thought I'd try to explain it in simple terms.
> 
> When electrical current flows, you have a magnetic field created around the wire. The opposite is also true: pass a wire through a magnetic field, and current will flow.
> 
> ...


Good explanation of chokem and why a ground wire must be well connected to the metal raceway if the ground is installed in a metal raceway. All that said, most fault current follows the neutral and bond wires (equipment grounds). If significan current is following the ground wire then there are other chokes in the system including open neutrals.


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## Big John (May 23, 2010)

brian john said:


> I am going to test this, I am sure I can pass 7,500-10,000 amps through a short #2 solid.


 So, I stole your thunder, Brian, but the high current set was too close and this was too easy for me to pass up. :tt2:

I used a piece of #4 stranded and pumped an average of 7.3kA through it in 0.08 second pulses, keeping the tester at a constant voltage for each test. 








I tried three passes and cooled it with water between each pass: 
7.04 kA
7.71 kA
7.24 kA









Then I put a piece of 1/8" steel in which I'd drilled a 1/4" hole. There was no bonding.








I got an average of 7.4kA:
7.61 kA
7.24 kA
7.30 kA









Doesn't appear to me the steel made one bit of difference, seeing how the average actually went *up*.

Just for kicks, I even put on a piece of 1/4" steel pipe thinking that would definitely make a difference, and was still getting currents well above the 7kA range. 









The only thing that *did *make any difference at all was the conductor temperature. When I didn't cool it at all, or cooled it inadequately, I started getting readings in the 6kA range. Considering that a stroke of lightning is gonna heat the heck out of the GEC, seems to me that is gonna have a much more negative impact on the conductor than any "choke effect" from passing through a steel meter can. 

I call shenanigans on the Kenny Clamp.


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## wendon (Sep 27, 2010)

What about in the event of a lightning strike? Say you run the GEC through a piece of EMT or through a wireway?


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## someonespecial (Aug 31, 2012)

Big John said:


> I call shenanigans on the Kenny Clamp.


Stop trying to disprove rumors with facts, that's not how the internet works.


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## rip (Jan 8, 2009)

*mighty ground*

Bridgeport has a new "mighty ground" fitting, the MCC-050 and 075 that is similar in function to the Kenny Clamp.
http://www.cesco.com/b2c/product/535878


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## Big John (May 23, 2010)

wendon said:


> What about in the event of a lightning strike? Say you run the GEC through a piece of EMT or through a wireway?


 I can't say, I don't know how you'd go about figuring that out.

It's gotta have an effect at some point, because current choking is a real phenomenon. So maybe the difference here is that my pulses were too small and the duration was too long. Maybe if I'd put a scope on the waveform I would've been able to see that the steel really was slowing down the rise-time, even if it didn't change the amplitude.


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## 8V71 (Dec 23, 2011)

What do these testers use to switch the current on and off?


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## jza (Oct 31, 2009)

Anyone have any pictures of these installed?


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## chicken steve (Mar 22, 2011)

~C_(OMG!)_S~


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## Magnettica (Jan 23, 2007)

I installed these things for a little while. Haven't seen them much at supply houses now for a few years. I envy the people who have the balls the introduce new products though.


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## kbsparky (Sep 20, 2007)

rip said:


> Bridgeport has a new "mighty ground" fitting, the MCC-050 and 075 that is similar in function to the Kenny Clamp.
> http://www.bptfittings.com/images/wh...ts Flyer.pdf


Bad link.


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## rip (Jan 8, 2009)

kbsparky said:


> Bad link.


http://www.cesco.com/b2c/product/535878


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## brian john (Mar 11, 2007)

8V71 said:


> What do these testers use to switch the current on and off?


You mean how do the high current test sets work?

The can run continuous current or jog/pulse the current. They use SCRs (I ASSUME)


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## 8V71 (Dec 23, 2011)

brian john said:


> You mean how do the high current test sets work?
> 
> The can run continuous current or jog/pulse the current. They use SCRs (I ASSUME)


What they use inside to switch. Must be huge whatever they are.


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## ElectricJoeNJ (Feb 24, 2011)

Here's a good one. So I'm working in a commercial warehouse. Numerous panels and transformers throughout the bldg. I have black buttons for the ground wire on the transformer going to bldg steel. I also have a separate service On the site. For this main breaker panel I ran a 1/2" EMT up and ran the ground wire to bldg steel through a romex Conn with the wire stripped at the conn. inspector failed me for this and wanted the ground wire in PVC to stop the "choke effect" BUT it gets better, he also failed my transformers and wanted Kenny clamps in place of the black buttons!! SMH


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## Magnettica (Jan 23, 2007)

ElectricJoeNJ said:


> Here's a good one. So I'm working in a commercial warehouse. Numerous panels and transformers throughout the bldg. I have black buttons for the ground wire on the transformer going to bldg steel. I also have a separate service On the site. For this main breaker panel I ran a 1/2" EMT up and ran the ground wire to bldg steel through a romex Conn with the wire stripped at the conn. inspector failed me for this and wanted the ground wire in PVC to stop the "choke effect" BUT it gets better, he also failed my transformers and wanted Kenny clamps in place of the black buttons!! SMH


WTH is a "choke effect"? 

What town is this so I know to add a pita factor?


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## ElectricJoeNJ (Feb 24, 2011)

Magnettica said:


> WTH is a "choke effect"?
> 
> What town is this so I know to add a pita factor?


Mahwah. John Lane is the inspector. Royal PITA


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## ponyboy (Nov 18, 2012)

ElectricJoeNJ said:


> Here's a good one. So I'm working in a commercial warehouse. Numerous panels and transformers throughout the bldg. I have black buttons for the ground wire on the transformer going to bldg steel. I also have a separate service On the site. For this main breaker panel I ran a 1/2" EMT up and ran the ground wire to bldg steel through a romex Conn with the wire stripped at the conn. inspector failed me for this and wanted the ground wire in PVC to stop the "choke effect" BUT it gets better, he also failed my transformers and wanted Kenny clamps in place of the black buttons!! SMH


Well it's in the code book. You can use steel conduit to run a GEC as long as you bond it to 250.66. If your installations are done to code especially the bonding and grounding part, who gives a shít about all them fancy science words


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## ElectricJoeNJ (Feb 24, 2011)

ponyboy said:


> Well it's in the code book. You can use steel conduit to run a GEC as long as you bond it to 250.66. If your installations are done to code especially the bonding and grounding part, who gives a shít about all them fancy science words


It was bonded. The problem is the inspector was saying it SHOULDNtT be bonded because of the "choke effect" but then failed the transformers because I didn't use Kenny clamps.


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## chicken steve (Mar 22, 2011)

well, so much for _black buttons_ then.....~CS~


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## ponyboy (Nov 18, 2012)

ElectricJoeNJ said:


> It was bonded. The problem is the inspector was saying it SHOULDNtT be bonded because of the "choke effect" but then failed the transformers because I didn't use Kenny clamps.


I read your post again more carefully and saw where I missed that part. As far as I'm concerned it's a legal install, I don't recall "choke effect" being referenced in the NEC. Around here though we can't get away with the rigid coupling to romex connector method. We need to use a connector with a bonding bushing on it. Sucks when you have to get a 3/0 terminated on a 1" bonding bushing.


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## ElectricJoeNJ (Feb 24, 2011)

ponyboy said:


> I read your post again more carefully and saw where I missed that part. As far as I'm concerned it's a legal install, I don't recall "choke effect" being referenced in the NEC. Around here though we can't get away with the rigid coupling to romex connector method. We need to use a connector with a bonding bushing on it. Sucks when you have to get a 3/0 terminated on a 1" bonding bushing.


I hear ya. This actually was done with a fromto. #4 wire, 150 amp service.


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## markore (Dec 7, 2011)

My jobs in PG county have passed inspection without it. Also, Pepco, the POCO, could care less.


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