# Dummy Fuses



## acro (May 3, 2011)

These seem to be hard to find and expensive when I do find them. Over 2x the cost of the similar fuse.

Can copper pipe and/or bar be used in their place?

I looked in my NEC index and did not find anything resembling that description.


If there is a specific article that addresses them, please let me know what it is.

Thanks


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## BBQ (Nov 16, 2010)

The code that would apply is 110.3(B).

'Listed and labeled equipment will be used per it's listing'

I don't think you would get any manufacture to say a piece of pipe is OK in the fuse holder.


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## Jlarson (Jun 28, 2009)

acro said:


> Can copper pipe and/or bar be used in their place?


Can you? Yes

May you? No 


I bet BBQ beats me to this.

Edit: I gotta type faster :laughing:


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## BBQ (Nov 16, 2010)

Jlarson said:


> Can you? Yes
> 
> May you? No
> 
> ...


Well yeah :jester:

Today was my last day of work until 6/20 you will be stuck with me more than normal. :laughing:


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## Dennis Alwon (May 9, 2009)

BBQ said:


> Today was my last day of work until 6/20 you will be stuck with me more than normal. :laughing:


Usually it is the wives who suffer in that situation. My wife teaches so she will be off this summer--- We'll see what our relationship is really made of now.


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## Jlarson (Jun 28, 2009)

BBQ said:


> Today was my last day of work until 6/20 you will be stuck with me more than normal. :laughing:


I'm hopping for a full day of field work to come up, too much office time lately plus I just came back from a week long vacation, I need something to hack. :laughing:


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## acro (May 3, 2011)

Figured so, I wonder why they are not more prevalent. Seems like Bussman is the only source.


Heck, I can put a label on the pipe.:whistling2:


I guess, I would not have an issue with it if they where priced the same as a fuse. I know by looking at them that they have to be cheaper to make than an actual fuse, yet they charge over 2x the price.


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## BBQ (Nov 16, 2010)

Dennis Alwon said:


> Usually it is the wives who suffer in that situation. My wife teaches so she will be off this summer--- We'll see what our relationship is really made of now.


When I see husbands and wives that work together I always wonder how the hell they do that. :laughing:


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## acro (May 3, 2011)

http://cgi.ebay.com/ws/eBayISAPI.dl...akeTrack=true&ssPageName=VIP:watchlink:top:en

I am looking closely and only see a MFG and part# and "this is not a fuse"


I suppose the part# would be enough?

Heck, I can't even see a voltage rating.


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## Jlarson (Jun 28, 2009)

acro said:


> Figured so, I wonder why they are not more prevalent. Seems like Bussman is the only source.


Ferraz Shawmut makes them too. About the same price as Bussman though.


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## acro (May 3, 2011)

BBQ said:


> When I see husbands and wives that work together I always wonder how the hell they do that. :laughing:



She get to be the boss?:laughing:


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## Mike_586 (Mar 24, 2009)

acro said:


> http://cgi.ebay.com/ws/eBayISAPI.dl...akeTrack=true&ssPageName=VIP:watchlink:top:en
> 
> I am looking closely and only see a MFG and part# and "this is not a fuse"
> 
> ...


They're 60A and I'm guessing 250V, the ratings should be stamped on them if I recall right.


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## tkb (Jan 21, 2009)

acro said:


> These seem to be hard to find and expensive when I do find them. Over 2x the cost of the similar fuse.
> 
> Can copper pipe and/or bar be used in their place?
> 
> ...


Why would you need them that often?
Are you in the habit of using the wrong disconnects?


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## acro (May 3, 2011)

I won't need them that often, but my thoughts where for the industry as a whole.

I do understand that once you have them, you probably won't replace them, but I was suprised that they seemed to be rare.

We contacted 3 of our electrical suppliers and only one privided a quote. And that one had to create part numbers for them as they apparently have never sold them before.

That tells me that grounded leg sytems are rather rare in this area, or the ones that do have them probably got their dummy fuses years ago.


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## don_resqcapt19 (Jul 18, 2010)

acro said:


> ...
> That tells me that grounded leg sytems are rather rare in this area, or the ones that do have them probably got their dummy fuses years ago.


Or they have actual fuses in the grounded leg. I have seen a number of them that way.


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## janagyjr (Feb 7, 2011)

don_resqcapt19 said:


> Or they have actual fuses in the grounded leg. I have seen a number of them that way.


I was under the impression (via school books and such) that you're not supposed to fuse the grounded leg? Did I miss something?


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## retiredsparktech (Mar 8, 2011)

acro said:


> That tells me that grounded leg sytems are rather rare in this area, or the ones that do have them probably got their dummy fuses years ago.


 The shop I worked at for 20 years had solid copper round and flat stock that we used instead of "B" phase fuses. We had them silver plated. I think they made them in the tool and die shop. An old shop that had corner grounded delta.


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## acro (May 3, 2011)

Correct, you are not supposed to.

I wonder if the older code allowed or even required the fuses?

Because we definitely have at least one grounded leg system here with no dummy fuses.


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## janagyjr (Feb 7, 2011)

It's good to know I didn't miss something. Perhaps things have changed since the "good old days"?


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## RePhase277 (Feb 5, 2008)

Corner grounded systems I have seen, at least the ones properly installed, used single phase breaker panels, and where fuses were used, a two pole disconnect.

Using three phase equipment on a grounded B system is a waste of money. 

Personally, if I were a* plant electrician* in charge of the equipment, I'd use copper rod or pipe. But as an *electrical contractor*, I would not go that route.

So, as a plant electrician, if the cost of dummy fuses is prohibitive, then you are faced with two cost saving code violation to choose from. You can either overfuse the grounded leg so it is rated higher than the other two, or you can use a non-listed jumper material such as pipe.

The only Code compliant way to do it is to use dummy fuses or wire that phase straight through.


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## Petric (May 5, 2011)

In my experience older fuses are required in rare case. We should not compromise with quality. I too, wonder if the older code allowed or even required the fuses? In some cases, may be the prices are higher or fluctuating.


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## acro (May 3, 2011)

Well, it won't be inspected, so it really is down to the most practical solution for us - I suppose.


I had thought of over fusing, but had decided against it as a long term solution. We have several renewable fuses that I could use to over-fuse also, but I think I will go a different route.


There are only 3 or 4 breakers, the majority of the disconnects are fuses.


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## ralpha494 (Oct 29, 2008)

Don't overlook 430.36 which says:

*430.36 - In Which Conductor.* Where fuses are used for motor overload protection, a fuse shall be inserted in each ungrounded conductor and also in the grounded conductor if the supply system is 3-wire, 3-phase ac with one conductor grounded.

I have a note under that article to have me read 240.22 and 430.52.


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## acro (May 3, 2011)

Well, that one(430.36) seems to directly contradict 240.22.


So, which one prevails? I can see that 240.22 would allow for a potentially safer installation, but 430.36 says it is OK to use fuses. Could this be a justification for over-fusing?


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## user4818 (Jan 15, 2009)

BBQ said:


> Today was my last day of work until 6/20 you will be stuck with me more than normal. :laughing:


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## HARRY304E (Sep 15, 2010)

> Originally Posted by *BBQ*
> _Today was my last day of work until 6/20 you will be stuck with me more than normal. :laughing:_


 



Peter D said:


>


:laughing::laughing:


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## Lone Crapshooter (Nov 8, 2008)

When I worked around corner grounded systems a piece of copper pipe was used.
If the customer has a engineering department or a contract engineer see what they will accept. 

LC


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## RePhase277 (Feb 5, 2008)

acro said:


> Well, that one(430.36) seems to directly contradict 240.22.
> 
> 
> So, which one prevails? I can see that 240.22 would allow for a potentially safer installation, but 430.36 says it is OK to use fuses. Could this be a justification for over-fusing?


I hadn't thought to check 430.36. But now that I have, it seems to prevail. In my 2005 code I have handy, 240.22 (2) gives 430.36 the lead in that case.


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## CraigV (May 12, 2011)

Just use the copper pipe. If you feel nervous, just wrap it in aluminun foil, or be really deluxe and use foil tape. Write "UL" on it with a Sharpie; that'll fool any EI who happens by. They can't prove it isn't listed, can they?


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## rexowner (Apr 12, 2008)

Jlarson said:


> Ferraz Shawmut makes them too...












For some reason, when I have seen this ad in EC&M the last couple of months it cracks me up.


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## acro (May 3, 2011)

Well, I suppose I just don't know which way to go quite yet. I did measure the different fuses to get a handle on what kind of pipe and bar stock I will need. Because i will probably go that route if I go with the dummy fuses.


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## RePhase277 (Feb 5, 2008)

acro said:


> Well, I suppose I just don't know which way to go quite yet. I did measure the different fuses to get a handle on what kind of pipe and bar stock I will need. Because i will probably go that route if I go with the dummy fuses.


Since 430.36 and 240.22 allow you to use fuses in the disconnects that feed motor loads, you can just leave them in where that's what they feed. In you plant, I imagine that is probably the majority of the loads.

It may turn out you only need a few dummies.


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## acro (May 3, 2011)

Yea, I can I see a distinction. If I have a fuseable disconnect feeding another sup panel that has a combination of loads, I would have a dummy fuse on the grounded leg. But if feeds a motor only, then the fuse is acceptable.

I suppose if I had a circuit that fed a sub-panel that only had motors connected to it, I could use regular fuses throughout.

But what about a circuit that would feen an electronic motor starter or vsd? Would those be clasified the same as the motors they are driving?


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## janagyjr (Feb 7, 2011)

Why not just use a regular fuse instead of a dummy fuse (or at least something listed that could handle the current)?


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## Jlarson (Jun 28, 2009)

I believe (I might be wrong cause I'm going off memory) 430.36 is concerning fuses used as overload protection, IMO in lieu of a starter or drive that provides OL protection.


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## janagyjr (Feb 7, 2011)

I'm sorry, I see the distinction but still do not understand the use of so-called "dummy fuses".


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## Jlarson (Jun 28, 2009)

Never mind; wrong thread


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## cabletie (Feb 12, 2011)

Jlarson said:


> I believe (I might be wrong cause I'm going off memory) 430.36 is concerning fuses used as overload protection, IMO in lieu of a starter or drive that provides OL protection.


You have a good memory


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## Jlarson (Jun 28, 2009)

cabletie said:


> You have a good memory


I did read most of 430 the other day so I should be able to remember most of it, I hope.


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## janagyjr (Feb 7, 2011)

I'm still lost on dummy fuses. Use normal real fuses on the right side of a motor starter for OL protection, then drive the motor, motor goes to neutral which is un-fused (or at least supposed to be) dummy or otherwise.


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## RePhase277 (Feb 5, 2008)

janagyjr said:


> I'm still lost on dummy fuses. Use normal real fuses on the right side of a motor starter for OL protection, then drive the motor, motor goes to neutral which is un-fused (or at least supposed to be) dummy or otherwise.


The OP is working on a system at a plant with a corner grounded delta system. So he has a grounded phase, which, like a neutral, can't have a fuse in it. The code says where used as motor overload protection however, that that phase can be fused.


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## Jlarson (Jun 28, 2009)

janagyjr said:


> I'm sorry, I see the distinction but still do not understand the use of so-called "dummy fuses".


Think about it, is it generally a good idea to open any other grounded conductor? The dummy fuse prevents that from happening.


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## janagyjr (Feb 7, 2011)

InPhase277 said:


> The OP is working on a system at a plant with a corner grounded delta system. So he has a grounded phase, which, like a neutral, can't have a fuse in it. The code says where used as motor overload protection however, that that phase can be fused.


Okay, I got that. But if you're using a dummy fuse as overload protection, doesn't that defeat the purpose? Or did I just duck under the point? ):



Jlarson said:


> Think about it, is it generally a good idea to open any other grounded conductor? The dummy fuse prevents that from happening.


So...why even put a dummy fuse there?!


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## cabletie (Feb 12, 2011)

> Okay, I got that. But if you're using a dummy fuse as overload protection, doesn't that defeat the purpose? Or did I just duck under the point? ):


More than likely there is another form of o.l. protection in the starter. He has a motor control center with buckets, disconnects, fuses and more than likely thermal over loads in series with the coil on the starters. I am assuming all of this. So the fuses are just being used for short circuit protection. In this case you would use two fuses for the un-grounded phases and a dummy fuse for the grounded phase. 

430.36 Fuses — In Which Conductor.
Where fuses are used for motor overload protection, a fuse shall be inserted in each ungrounded conductor and also in the grounded conductor if the supply system is 3-wire, 3-phase ac with one conductor grounded.

The second part above would be for a 3 phase corner grounded delta where fuses are used to provide over load protection. If over load protection is already provided it would be safer if not required to install a dummy fuse in the (third phase) grounded conductor.

240.22 Grounded Conductor.
No overcurrent device shall be connected in series with any conductor that is intentionally grounded, unless one of the following two conditions is met: 
(1) The overcurrent device opens all conductors of the circuit, including the grounded conductor, and is designed so that no pole can operate independently. 
(2) Where required by 430.36 or 430.37 for motor overload protection.


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