# MC Connectors requiring locknuts???



## scottfwelch (Feb 16, 2009)

I heard a rumor that there may be an upcoming IBC code that requires locknuts on all MC connectors/fittings... It's supposed to have something to do with recent siesmic shake tests.... this would (in CA) no allow use of Arlington Industires Snap Connectors (38AST, 40AST etc..) Can anyone confirm or deny and provide a document for me?


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## MDShunk (Jan 7, 2007)

I doubt very much that something which would apply primarily to CA would ever make it into the IBC. The IBC's electrical section is more or less a condensed NEC.


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## scottfwelch (Feb 16, 2009)

Thanks, 

Let me kinda rephrase... I guess I mean I heard the rumor in CA, not that it will specifically apply _in CA only.. _Is there any truth to the locknut portion of the rumor?


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## rlc3854 (Dec 30, 2007)

Has California abandoned the UBC and adopted the IBC? Go to the California Building Code web site and check out title 24 part 7 (electrical), and check out the seismic section as well.


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## rexowner (Apr 12, 2008)

rlc3854 said:


> Has California abandoned the UBC and adopted the IBC? Go to the California Building Code web site and check out title 24 part 7 (electrical), and check out the seismic section as well.


California is going to the IBC, but that doesn't change
the basis of the Electrical Code.

2007 CEC (California Electrical Code) is based on
2005 NEC. Our very expensive bureaucracy makes 
sure we are always behind the rest of the country.

I haven't heard anything about a rumor of locknuts for
MC. The only two hits on a search for "MC cable" at
the California Building Standards Commission website
point to two documents saying that Article 330
(MC cable) is adopted without amendments.


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## BryanMD (Dec 31, 2007)

scottfwelch said:


> I heard a rumor that there may be an upcoming IBC code that requires locknuts on all MC connectors/fittings...



Does the IBEW have this much influence in CA?


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## rlc3854 (Dec 30, 2007)

BryanMD said:


> Does the IBEW have this much influence in CA?


Huh? How did you arrive at that (IBEW)?


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## scottfwelch (Feb 16, 2009)

hahaha... actually I'd say yes.. depending on the contractor and or job.. Seems like they'll do anything it takes to milk out a job..

On my topic, I heard that years ago that a manufacturer did a shake test with ENT and EMT... ENT did NOT fail but the EMT with set screw connectors and locknuts completely shook loose and was hanging by Tbar wire.. this test was done because the IBEW was saying ENT wasn't secure... oops


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## rlc3854 (Dec 30, 2007)

So as to your thinking the California Certification for electricians working for a C-10 electrical contractor was all about the IBEW trying to stop untrained workers? Or the really biggy stop merit shops from hiring qualified workers.


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## cptkinguru (Jan 15, 2008)

I heard, I heard, and it's all the fault of the IBEW. Interesting.


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## Rockyd (Apr 22, 2007)

Pretty weak blaming the IBEW. I'm in the next state over, and hate that they are trying to Californicate Nevada! More socialism and despotism delivered by the the politicians of the last four years. That would be Shrub, Mcpain, Peelousy, Harry greed, and Obummer, none of them worth a damn.

Lock nut on MC? To serve what purpose? 250.118(10) Should fully cover the scope needed.


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## Bkessler (Feb 14, 2007)

Ibew did lobby gray davis for the electrical certification, there thinking was the ibew j-mans card would be good enough and they would not have to take the certification exam. But it backfired to some degree.


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## jack103x (May 17, 2009)

*locknuts*

I had an old timer once tell me this"The only thing we have to sell is our labor".


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## LJSMITH1 (May 4, 2009)

scottfwelch said:


> I heard a rumor that there may be an upcoming IBC code that requires locknuts on all MC connectors/fittings... It's supposed to have something to do with recent siesmic shake tests.... this would (in CA) no allow use of Arlington Industires Snap Connectors (38AST, 40AST etc..) Can anyone confirm or deny and provide a document for me?


 
There is no such proposal that I am aware of in CA (and I am in the fittings business). 

As for the logic, it would seem to me more likely that a locknut version would be able to come loose because the nut could back off completely if not fully tightened properly. The snap-ins (by the very nature of the design) can maintain the required contact pressures and retention capability to carry the specified ground fault current, even probably during some vibration. 

Let me clarify this by saying there is no vibratory testing requirement in UL514B, and there is no test data to back up my statement. However, the snap-in fitting must be mechanically disengaged to get it out of the box knockout, as it will not just "fall out". Some snap-in's are harder to remove than others (i.e. Arlington's split ring must be pried off, vs. Bridgeport's just needs to have one locking tab pushed down with a screwdriver). Both do the job in accordance with UL514B.

The overall logic of any properly installed, MC/AC fitting vibrating loose during an earthquake doesn't make sense. Most vibrational forces would be absorbed by the flexibility of the MC/AC cable and not the fitting attached to the enclosure. I would think an EMT or RMC conduit connector would have the most vibratory forces acting on it due to the rigidity of the conduit being a good conductor for vibration. This would be an interesting study if some University were to take it on...:thumbsup:

I feel that there possibly may be another agenda behind this rumor which has nothing to do with 'seismic forces'...


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## Celtic (Nov 19, 2007)

LJSMITH1 said:


> There is no such proposal that I am aware of in CA (and I am in the fittings business).
> 
> As for the logic, it would seem to me more likely that a locknut version would be able to come loose because the nut could back off completely if not fully tightened properly. The snap-ins (by the very nature of the design) can maintain the required contact pressures and retention capability to carry the specified ground fault current, even probably during some vibration.
> 
> ...



I think the whole concept of requiring locknuts on all MC connectors/fittings is kind of silly ~ 250.118 does not list the jacket as an EGC. 
So what's the point of a locknut?
The Arlington snap-ins fit the application just fine, IMHO :thumbsup:


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## LJSMITH1 (May 4, 2009)

Celtic said:


> I think the whole concept of requiring locknuts on all MC connectors/fittings is kind of silly ~ 250.118 does not list the jacket as an EGC.
> So what's the point of a locknut?
> The Arlington snap-ins fit the application just fine, IMHO :thumbsup:


 
250.118 may not specifically list the MC/AC cable jacket as an EGC, but I can tell you that UL514B does require the cable fitting to electrically bond to the sheath of the MC/AC cable - and handle a ground fault current. The current is typically limited by the sheathing's ability, not by the snap-in's design.

Southwire's MCap cable utilizes the sheath as an EGC, and many snap-ins are listed for use with that type of cable.


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