Service Entrance Conductor

[techresource]

We are replacing a 200 amp 120/240 residential panel. One conductor is Aluminum 4/0 the other is copper 2/0. Is it permissible to use two types of service conductors in the same panel. I can't see where this is prohibited by the code.

 

[russ]

Re: Service Entrance Conductor

While it's not a common practice, there's nothing in the code prohibiting you from having copper for one phase and aluminum for another.

Russ

 

[sparkmantoo]

Re: Service Entrance Conductor

thats tacky though.

 

[maylo1st]

Re: Service Entrance Conductor

since they will not be connected there would not be a problem however for workmanship i would change to all of one or the other and alum is cheaper

 

[bphgravity]

Re: Service Entrance Conductor

This really sounds like a hypothetical question. I can not imagine a qualified electrician performing this installation. What are the chances that you have just enough 4/0 Al and 2/0 Copper for one length each and not enough to make the complete installation with one type? I would not accept this regardless if the code allows it!

 

[iwire]

Re: Service Entrance Conductor

Bryan, Not that I would do this and I agree it is unusual and tacky.

What basis could you fail this on?

This is similar to a question that was presented in a 15 hour code update class.

"If running parallel conductors would one set of phase conductors have to have the same properties as the other sets?"

The answer is no.

Bob

 

[bphgravity]

Re: Service Entrance Conductor

Bob, I am talking from a personal standpoint and not as an AHJ. Specificaly, if I was the homeowner, I wouldn't pay for this work. If I was the installers boss, I would fire him. If I was the installers instructor, I would suggest against it. From a code standpoint, I agree it is not prohibited.

 

[iwire]

Re: Service Entrance Conductor

I got you now Bryan, around my way this installation would warrant a "Dope Slap"

 

[iwire]

Re: Service Entrance Conductor

You know as I think on this a little, I can not come up with any legitimate reasons for my dislike of this installation. :roll:

As long as both conductors are sized correctly safety can not be used as a reason not to do this.

But it really seems "Wrong"

 

[lady sparks lover]

Re: Service Entrance Conductor

i don't see it as against code, but the materials bonded together could lead to corrosion, i think.

Originally posted by iwire:
You know as I think on this a little, I can not come up with any legitimate reasons for my dislike of this installation. :roll:

As long as both conductors are sized correctly safety can not be used as a reason not to do this.

But it really seems "Wrong"

 

[bphgravity]

Re: Service Entrance Conductor

I think it has a little more to do with than what looks good or what we are used to. This provides a confusing troubleshooting issue and also identification issues. Before things became code, code, code, and way before my time, the craftsmanship and workmanship of a job meant more than anything. I feel this is just another example how someone could "beat" the code if they really wanted to because the code cannot possibly cover every issue. I think I will submit a proposal for 2005.

 

[jxofaltrds]

Re: Service Entrance Conductor

310.15(B)(6)

Since this is not a cable it must be individual conductors in a raceway.

IMC 342.22 takes you to Chapter 9 Table 1

RMC 344.22 ditto

RNC 352.22 ditto

Get the idea.

This is for conductors of the same type (althought it does not say that)

In the above application you could not figure fill. Hence a violation.

Most of all "workmamship" would fail this.

Mike P.

 

[bphgravity]

Re: Service Entrance Conductor

Mike, I don't understand your point. Why can't you figure conduit fill using table 1? If this is a service entrance, it will have two ungrounded and one grounded conductor. Therefore, the conduit cannot be filled to over 40%. The dimensions of the conductors can be found in Table five and calculated into Table 4.

 

[iwire]

Re: Service Entrance Conductor

Mike, I do not see how Chapter 9 Table 1 would have anything to do with this, we have to figure fill with different size of conductors in the same raceway all the time.

Look at the 310.4 the paragraph right under 1 through 5 and the FPN below it, looks like they intentionally left this as a possibility for parallel conductors, so wouldn't be hard to say poor workmanship when applied to single conductors.

Remember I said I don't like it either but I believe it is code compliant.

 

[don_resqcapt19]

Re: Service Entrance Conductor

Bryan,

I think I will submit a proposal for 2005.

Way too late for a 2005 proposal, they were due last November. The proposals for the 2008 code will be due in November of 2005.
Don

 

[bphgravity]

Re: Service Entrance Conductor

Thanks Don, got ahead of myself. Or should I say behind myself?

 

[jxofaltrds]

Re: Service Entrance Conductor

BH & BB

Thanks for questioning.

Chapter 9 FPN#1 "....common conditions" .... "proper cabling".

I would contend that this is not a common condition or is it proper cabling.

Mike P.

 

[hurk27]

Re: Service Entrance Conductor

110.12 Mechanical Execution of Work.

Would this do?

 

[david luchini]

Re: Service Entrance Conductor

Mike,

I'm not sure about your reference to Chapter 9, FPN #1. First of all, the fine print note is not an enforcable part of the code (see 90.5(C)). Secondly, the FPN #1 does not say that Table 1 can only be used in "common conditions," it says that certain conditions may require consideration of larger conduit size or lesser conduit fill.

Dave

 

[jxofaltrds]

Re: Service Entrance Conductor

Dave

I'm not sure either. I know the FPN is not enforceble.

Would 110.8 apply? I am not aware of a code reference that allows mixing of conductor sizes for services, feeders or branch circuits.

Mike P.