Code Question For Generator Wiring

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EL_Ken

Member
Location
Wareham, MA USA
I first wrote to Mike Holt about this and he referred me to Article 725. I have read up on Article 725 and could not find definitive enough wording to satisfy my electrician. I should have provided Mike with a more detailed question.


I apologize for this post being so long, but you know better than I that details matter in questions of code.

I am installing a Generac natural gas powered generator with a 200 amp whole house transfer switch. In addition to the power feed between the generator and the transfer switch, there are six "control" wires.

Generac "recommends" #18 AGW wire for these six lines if the length is under 115 feet. The actual length is 40 feet. My electrician is insisting on 14 AGW, saying because some are not "low voltage", the minimum allowed AGW is 14. The town wiring inspector seemed to only care that the insulation was rated for 600 volts.

Running six 18 AGWs would be a lot easier to string than 14s.

Three of the six wires are low voltage control wires. Two of the wires are on 5 amp fast acting fuses and carry 220 volts to the generator so that it can sense when the street power goes out or comes back on.

The last wire is of most concern to my electrician. It carries 120 volts to the battery charger that is contained within the generator. This wire is also on a 5 amp fast acting fuse.

As I read Article 725, Class 2 is excluded because of the 100VA limit. Class 3 is excluded due to the 1 amp limit. This leaves Class 1. I don't see any restrictions that would electrically disqualify any of these lines from Class 1 status, but the line to the battery charger doesn't seem like it would be classified as a "Control Line" and could be considered as non-qualifying because of it's usage.

Questions:

1. Does the battery charger line qualify as an Article 725 Class 1 line? If so, is there any specific documentation that would help convince my electrician that this is the case.

2. Is my electrician correct in saying that this must be a 14 AGW line? If so, which of the six lines have to be 14 AGW?

3. Is there a section of code I could read up on (other than 725) that might address this situation?

Thanks for any information you can provide.

Ken
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roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
I am trusting you when you say you have an electrician doing this wiring and with that said, you should let him do what he wants.
With the exception of small increase in price why would you care if he used a larger conductor than what is specified?

Roger
 

LIM

Member
Location
NC
I agree. Are you looking for maybe a $100 cost savings for a 250ft run of wire? Personally I would never want the possibility of a wire failing/shorting before the fuse or ocpd.
 

ceb58

Senior Member
Location
Raeford, NC
I am trusting you when you say you have an electrician doing this wiring and with that said, you should let him do what he wants.
With the exception of small increase in price why would you care if he used a larger conductor than what is specified?

Roger
I also agree with what Roger has said. Look at it this way #14 is a common size to stock #18 is not. It may wind up costing more to do it in 18 vs 14. Also if you decide to install the winter kit on the generator it connects to the N1 N2 connection in the generator. Although it would only add about 0.5 amps to the circuit why push it.
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
I also agree with what Roger has said. Look at it this way #14 is a common size to stock #18 is not. It may wind up costing more to do it in 18 vs 14. Also if you decide to install the winter kit on the generator it connects to the N1 N2 connection in the generator. Although it would only add about 0.5 amps to the circuit why push it.
Disclaimer: I'm not a Generac whiz, nor do I do much Residential.

True, but 16 TFFN is pretty common.

Generally I am a fan of installing per the published spec. My question is: Does the #14 fit the terminal blocks that are speced to take #18?

I dnn't know the answer, but the installers on here should.

ice
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
I am trusting you when you say you have an electrician doing this wiring and with that said, you should let him do what he wants.
With the exception of small increase in price why would you care if he used a larger conductor than what is specified?

Roger
I think Roger said it all. If you were trying to do this yourself we would be prohibited from giving you advice since you are not in the industry. I don't think we should be giving you any advice to second guess your electrician either. Let him do his job. If you don't like it get somebody else.

-Hal
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
Disclaimer: I'm not a Generac whiz, nor do I do much Residential.

True, but 16 TFFN is pretty common.

Generally I am a fan of installing per the published spec. My question is: Does the #14 fit the terminal blocks that are speced to take #18?

I dnn't know the answer, but the installers on here should.

ice
Just a heads up, I know Ceb58 and generator installs for the State of NC is a big part of his everyday activities.

Roger
 

ceb58

Senior Member
Location
Raeford, NC
Disclaimer: I'm not a Generac whiz, nor do I do much Residential.

True, but 16 TFFN is pretty common.

Generally I am a fan of installing per the published spec. My question is: Does the #14 fit the terminal blocks that are speced to take #18?

I dnn't know the answer, but the installers on here should.

ice
Never really deal with 16 or 18 except as wiring inside of control panels. The last residential ATS I installed I used #12-2 NM to j boxes on the side of the house and changed over to 12 thwn in pipe to the generator. There was no problem landing it under the N1 N2 and T1 terminals

Just a heads up, I know Ceb58 and generator installs for the State of NC is a big part of his everyday activities.

Roger
Will be coming your way, probably after the Holidays. Have got to meet with David to go over a built on site building in Bryson City. We'll do dinner :happyyes:
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
Will be coming your way, probably after the Holidays. Have got to meet with David to go over a built on site building in Bryson City. We'll do dinner :happyyes:
Sounds good, we'll make David stay and buy. :D

Roger
 

EL_Ken

Member
Location
Wareham, MA USA
Disclaimer: I'm not a Generac whiz, nor do I do much Residential.
True, but 16 TFFN is pretty common.
Generally I am a fan of installing per the published spec. My question is: Does the #14 fit the terminal blocks that are speced to take #18?
I dnn't know the answer, but the installers on here should.
ice
Thank you for all that answered.

1. The terminals will take much larger wire because for longer lengths, Generac recommends thicker wire.

2. The electrician is semi-retired and is a friend of mine and we are doing the work together. He has never installed a generator before. He lives 1:15 drive from here and doesn't get to my area too often. I'm trying to make things easier for both of us because the path between the generator and the transfer switch is not an easy one.

3. I'm going to order all the wire that is necessary. I found a place that carries almost anything and will ship it to me at a reasonable price, so having a common size does not come into play.

4. We have a permit from the town and I want no chance of failing an inspection.

5. My goals are to have the easiest install that is 100% up to code.

Ken
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EL_Ken

Member
Location
Wareham, MA USA
I think Roger said it all. If you were trying to do this yourself we would be prohibited from giving you advice since you are not in the industry. I don't think we should be giving you any advice to second guess your electrician either. Let him do his job. If you don't like it get somebody else.
-Hal
To be clear, I live in Massachusetts where as a single family homeowner I have the legal right to do all of the electrical work within my home. I have exercised that right for the past 40 years. I have often brought things up to code which were not before I got there. I have also professionally done computer and telephone wiring in office buildings.

Under the Massachusetts law, I can not pay anyone else to help me or do the work for me if it is done in my name. In the case of the generator, I decided that it was a big enough job that I would pay an electrician to help me and I would have it done under their name. This means that I have to go along with anything they say, but I still have every right to try to convince them to do it a different way if I feel that my way is better. The only way I can know if my ideas are better is to educate myself in what is allowed under the code. I was not asking for advice, I was asking for a clarification of the code.

I am certain that any information provided here in education or interpretation of the electrical code could not in any way be considered illegal in any jurisdiction.

Ken
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hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
The electrician is semi-retired and is a friend of mine and we are doing the work together. He has never installed a generator before. He lives 1:15 drive from here and doesn't get to my area too often.
Ahh, so this friend of yours is allowing you to do the work in his name under his license. I don't know if that's legal in MA. Your questions shouldn't be allowed here. You are a homeowner, not in the trade.

-Hal
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
I am not doing work in his name. I am acting as his helper.
Ken, even with your EE back ground I have to agree with hbiss, this is borderline DIYer and with that said, I am closing the thread in accordance with the forum rules.

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Roger
 
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