Rangers38
Have a project that I will be installing a 22KW generator with two separate 100 Amp transfer switches. The application is a residential service, 2 family with two separate utility meters. Want to use one generator to power up both households. Question is how are the transfer switches wired? Do you need individual feeds from generator? Control circuits? Have installed many in the past, this is the first with more than one switch. Any help would be appreciated
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78buckshot
Around this neck of the woods code won't allow it. Need a separate generator for each address.
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grsthegreat
I tried to do that on a property where the owner had 2 houses on 2 separate switches, and the state electrical inspector would not allow it. But if your state does allow it, you need to run the full 6 control wires to 1 switch, and then loop the Black, Red and white (0,23 and 194) wires between switches. The T1 and N1 and N2 wires MUST ONLY land onto 1 switch.
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Rangers38
Can I ask which state you are in? I would think the elctrical code should be the same in all states per the NEC. I understand the looping of the control circuit. That's what I was proposing to do, just wanted an opinion. I would think I would also need to junction box the generator feed, than run to each switch for supply?
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nrp3
Oh if it were that simple..., local and state amendments are very common. Different interpretations are common too. I?m doing both halves of a condo, with three switches and locally no one seems to mind, it?ll have a drawing with locations of disconnects, switches, propane tanks, etc for the fire dept by their request at the conclusion.
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Brian Baughman
It's not an NEC issue, but a building and zoning issue. Check with your local building inspector to see if they will allow this type of installation.
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Rangers38
I had asked my local electrical inspector a while back and he didn't have a problem with it. I applied for a permit to upgrade the electrical service to the house with with a 2 gang meter pan, and also on same permit indicated a 22kw gen, with 2 100 amp switches. So, hopefully all is good because the permit was approved. NJ here. I also understand the difference in some states with additional regulations on top of the NEC. It always boils down to interpetations, and authority having jurisdiction
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zen
grsthegreat;n60083 wrote:
I tried to do that on a property where the owner had 2 houses on 2 separate switches, and the state electrical inspector would not allow it. But if your state does allow it, you need to run the full 6 control wires to 1 switch, and then loop the Black, Red and white (0,23 and 194) wires between switches. The T1 and N1 and N2 wires MUST ONLY land onto 1 switch.


Can't hook all six wires to both switches?
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Peddler
No reason to hook the N-1, N-2, T-1 to both. You do need to hook 23 & 194 to both switches.
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zen
Peddler;n60105 wrote:
No reason to hook the N-1, N-2, T-1 to both. You do need to hook 23 & 194 to both switches.


Would it be a hazard if done that way or it doesn't matter?
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ceb58
Rangers38;n60090 wrote:
I had asked my local electrical inspector a while back and he didn't have a problem with it. I applied for a permit to upgrade the electrical service to the house with with a 2 gang meter pan, and also on same permit indicated a 22kw gen, with 2 100 amp switches. So, hopefully all is good because the permit was approved. NJ here. I also understand the difference in some states with additional regulations on top of the NEC. It always boils down to interpetations, and authority having jurisdiction


That's fine. You only had one service, meaning there was only one service lateral to the building. Is this a duplex apartment or is it 2 completely separate buildings with 2 completely separate services.
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grsthegreat
zen;n60108 wrote:


Would it be a hazard if done that way or it doesn't matter?


the system wont work. after it transfers, you will blow the N1 and N2 fuses. This is why Generac issues a notice about hooking up multiple switches.
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UPS
zen;n60108 wrote:


Would it be a hazard if done that way or it doesn't matter?

If one of the service disconnects were to be shut off, you would be back-feeding the associated panel via those lines. Most likely the 5 amp fuses would blow, except if there were no load on that panel, in which case it would be unexpectedly energized.
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zen
grsthegreat;n60113 wrote:


the system wont work. after it transfers, you will blow the N1 and N2 fuses. This is why Generac issues a notice about hooking up multiple switches.


I didn't find that notice in the diagnostic repair manual.Is there a list on generac site just to see if i'm missing something else?
And ty all for advices. It is much appreciated.
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JayH
zen;n60099 wrote:


Can't hook all six wires to both switches?


Absolutely don't do this. You'll be tying the two utility feeders together through the N1 and N2 5-amp fuses in the switches. As user Peddler states, just hook up the 0, 23, and 194 control wires to both switches. If some very odd condition causes the power to fail to only one service (unpaid electric bill, meter fault, etc.) either both houses will transfer or neither will depending on which is sourcing N1 and N2.
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zen
They are both connected under the same meter feeding one panel each in the same house.
But will follow recommandations and already took arrangement to be there to unhook N1,N2 and T1 in one of the switches.
That's why i was asking if those notice issued by generac were accessible I would like to read it if there's more.
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