# generator wiring?



## az-guy (Feb 9, 2008)

my company has started wiring generators in and i have wired a few in but the other day my boss asked me to make sure i am phasing the box so we dont overload the neutral so if i have a 7kw generator and the 8 circuits are on the left and are on circuits 1,3,5,7,9 that is phase fine when i remove them now if one phase has say 6 circuits going to my transfer switch and 2 circuits from the other phase do i need to repositon other breakers to the phase with 2? i hope this makes sense


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## mdshunk (Mar 13, 2005)

It is impossible to overload the neutral by not having your load balanced among the phases since your neutral is full sized in generator installs. Your boss is retarded.


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## az-guy (Feb 9, 2008)

thanks- the generators are carrier and in the manual and the dvd they dont mention that in anyway like i said if i move 7 breakers to the transfer switch on phase 1,2,5,6,9,10 i dont have to move breakers from 3,4,7,8,11,12 to balance the load so we dont overload the neutral, what do you mean your neutral is full sized??


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## mdshunk (Mar 13, 2005)

az-guy said:


> ...to balance the load so we dont overload the neutral, what do you mean your neutral is full sized??


You keep saying that, but listen to reason here... it is not possible to overload the neutral in your application. 

Is this residential? There is no possible way to balance anything in a residential application anyhow, due to the diverse load profile.


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## az-guy (Feb 9, 2008)

yes residential, i get its not possible to overload the neutral, he claims he has a electrial buddy that went out and saw how we wired them and told him about phasing the panel,they are pretty nice generators, i do hvac so we started doing these this past year, wiring them in we have the transfer switch , with the 2' whip and the 30' whip for outside, i am thankful for your quick response


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## mdshunk (Mar 13, 2005)

az-guy said:


> yes residential..


Okay, your boss is twice as retarded as I originally thought. There is no way to balance anything residential. People come and go, move about in the house, and thus the load is in constant flux.


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## az-guy (Feb 9, 2008)

the only thing in the video that says if you have a 2 circuits that share the same neutral you have to move both circuits or dont move them at all


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## mdshunk (Mar 13, 2005)

az-guy said:


> the only thing in the video that says if you have a 2 circuits that share the same neutral you have to move both circuits or dont move them at all


Yeah, but that's just MWBC 101.


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## az-guy (Feb 9, 2008)

thank you for the response,and the answers to my questions so the next time i wire in a generator i wont have to worry about what phase i take of for my back up circuits of


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## mdshunk (Mar 13, 2005)

Just make sure both conductors of any MWBC are on opposite legs, and that's all you need to worry about.


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## az-guy (Feb 9, 2008)

mdshunk said:


> Just make sure both conductors of any MWBC are on opposite legs, and that's all you need to worry about.


hate to ask but what does mwbc,


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## mdshunk (Mar 13, 2005)

Multiwire branch circuits.


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## az-guy (Feb 9, 2008)

mdshunk said:


> Multiwire branch circuits.


thats like we were saying if 2 circuits share the same neutral put them on opposite phases got it, and i dont have to worry about phasing the main panel thank you


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## mdshunk (Mar 13, 2005)

az-guy said:


> thats like we were saying if 2 circuits share the same neutral put them on opposite phases got it, and i dont have to worry about phasing the main panel thank you


Yes sir. Sounds like you've got it all straight now. 

If you ever put in a genny in a commercial setting, where the loads are fairly continuous, you should balance the load out as a matter of good practice. The generator will thank you (run cooler), but it doesn't have anything to do with the neutral. 

I think Carrier generators are just re-badged Generacs, right?


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## az-guy (Feb 9, 2008)

you got it just with a carrier name plate on it


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## mdshunk (Mar 13, 2005)

az-guy said:


> you got it just with a carrier name plate on it


Lennox has a generator too, but I forget who the OEM is for theirs.


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## Woodshed (Feb 1, 2008)

mdshunk said:


> Just make sure both conductors of any MWBC are on opposite legs, and that's all you need to worry about.


Why do the the conductors have to be on opposite legs?


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## mickeyco (May 13, 2006)

Woodshed said:


> Why do the the conductors have to be on opposite legs?


It looks a lot nicer that way.





So as not to overload the neutral.


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## Ponsse (Dec 12, 2007)

Woodshed said:


> Why do the the conductors have to be on opposite legs?


 
To prevent overloading the neutral. If they're both on the same leg, the neutral will carry the current for both of them instead of the the current circulating back and forth between the 2 hots on opposite legs.


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## woodchuck2 (Feb 27, 2008)

Sounds very similar to a Guardian generator which i sell/install. Even if there was a possible way to "overload" the neutral from the transfer switch to the main panel you will find that the wiring for the transfer switch is a stranded wire and also oversized for the load that it is listed for. Example a 15 amp circuit is wired with 12ga stranded, 20 amp circuit is wired with 10ga stranded and are more than capable for higher amperage. If i remember correctly the 7k Guardian transfer switch has 6ga stranded copper for the conductors and neutral.


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## az-guy (Feb 9, 2008)

exactly- the transfer switch is pre wired so all i do is take a wire off the breaker they want to back up and wire nut it in the main box, and with the common wires i take all of them to the neutral bar in the main panel


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## Woodshed (Feb 1, 2008)

Ponsse said:


> To prevent overloading the neutral. If they're both on the same leg, the neutral will carry the current for both of them instead of the the current circulating back and forth between the 2 hots on opposite legs.


Is this the correct way to wire a residential electrical panel that is not using a transfer switch?


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## az-guy (Feb 9, 2008)

if they share the same neutral like say you have a 3 wire circuit that has 1 black and a red and a white in the box you would have the circuits on 1,and 3 those are on opposite phases of the panel if you put the circuits on 1,2 they would be on both phases


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## Woodshed (Feb 1, 2008)

az-guy said:


> if they share the same neutral like say you have a 3 wire circuit that has 1 black and a red and a white in the box you would have the circuits on 1,and 3 those are on opposite phases of the panel if you put the circuits on 1,2 they would be on both phases


_To prevent overloading the neutral. If they're both on the same leg, the neutral will carry the current for both of them instead of the the current circulating back and forth between the 2 hots on opposite legs._


So,1 and 3 are "opposite" legs and 1 and 2 are the "same" leg? I'm also assumimng that we are taling about a panel that 1 through 39 (pick a number) are on the left side of the panel and 2 through 40 are on the right side of the panel if it's a 40 circuit panel.


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## mdshunk (Mar 13, 2005)

I'm not even sure I understand what we're talking about any more. It started as balancing a panel, then ended as properly wiring multi-wire branch circuits. Two different things.


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## woodchuck2 (Feb 27, 2008)

az-guy said:


> exactly- the transfer switch is pre wired so all i do is take a wire off the breaker they want to back up and wire nut it in the main box, and with the common wires i take all of them to the neutral bar in the main panel


Your transfer switch should have one large "6 or 8ga" neutral wire that should be connected to the neutral bus bar that the incoming service neutral is connected to. All the other neutrals that i beleive you are talking about are for AFCI breaker circuits. The transfer switch is prewired for these breakers and is up to you to use them or not. I use them when the AFCI breaker is called for to keep withen code but if not then i zip-tie them together and lay them at the bottom of the panel. I have also used them for piggy back circuits in the transfer switch if the HO wants more circuits than what the transfer switch offers but you musnt overload the generator and be sure to properly mark the wire as a hot so it is not mistaken down the road, i usually wrap it with tape so it is black"line" instead of white"neutral".


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## Electric_Light (Nov 25, 2007)

What the hell are you running, a computer lab? You can only overload a full size neutral if you're running a bunch of computers and electronics, as they have an astronomical amount of 3rd harmonic. 

If you're running loads so rich in 3rd harmonic, you need to seriously oversize the generator anyways which means it will come with larger conductors. So, neutral overload is unlikely. 

BUT.... you still need to balance the load across all phases. Phase imbalance will cause pulsating torque load on the engine and increases vibration which tears apart the generator.

Is this a 208Y/120v or a 480Y/277v generator?

And why the hell are you installing a polyphase generator in on a residential property??


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## mdshunk (Mar 13, 2005)

Electric_Light said:


> BUT.... you still need to balance the load across all phases. Phase imbalance will cause pulsating torque load on the engine and increases vibration which tears apart the generator.


In commercial work. This is 10,000% impossible to do with resi work.


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## az-guy (Feb 9, 2008)

residential, houses ,NOT commercial standard 240/120 generator


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## Electric_Light (Nov 25, 2007)

az-guy said:


> residential, houses ,NOT commercial standard 240/120 generator



That's single phase then. why were you talking about multiple phases?


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