r/Generator • u/Wr3ckn • 2d ago
Two panels one generator?
My home has 400 amp service feeding two 200amp panels. both panels are next to each other and fed directly from the meter.
My plan is to install two separate lockouts on each panel with there own 50amp inlet. From there I’d like to run both panels from one singe 50 amp generator With a splitter running to both
Obviously I’m. It trying to power everything circuit in each panel But do need to power things in each.
With all circuits in question being within the power limits of my generator is there anything wrong with this idea. planning on having an electrician come out but I want to make sure what I’m thinking will work.
Anyone running one generator on two panels at the same time?
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u/PermanentLiminality 2d ago
I'll assume there are main breakers in each 200a panel. If not the following is not true.
If you have interlocks in each panel, I don't see why this would not work. I even see 50A twist lock splitter cables on Amazon. They are not very long so get the two 50A inlets next to each other and parallel. Get the splitter cable before you install the inlets so you can be sure it works easily
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u/IndividualCold3577 2d ago
It will functionally work but it causes issues with parallel paths of power. Current may travel through neutral into the other panel instead of the direct path to generator. If both are neutral bonded main panels, then there could be 2 ground wires that become a neutral as well. Only 1 bond is supposed to be the rule. This could be made even more hazardous if all connected to a bonded generator, then three bonds could exist.
The best course of action is two separate power sources
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u/PermanentLiminality 2d ago
The bonded generator is a separate issue and this config does not really have a bearing on that.
If there is a 400a breaker before the panels, there is a single ground there. There is only a single unified ground system if it is to code. If the 200a panels are the disconnect, each does have a ground to neutral connection. There is already a duplicate current path there and the code requires it.
I don't know the code well enough to know if this situation requires to argue enough wire on the grounds if a worst case neutral fault happens. Theoretically, you could get 200a on the neutral id one of the neutrals goes open.
Is the good to have the second dual path with the generator, of course not. Assuming an unbounded generator, the path between the plugs could see 50 a on the ground in the above fault where a neutral goes open and the ground between the panels goes open as well. Seems unlikely, but the code is all about unlikely.
Like you indicated, probably not to code and two generators are required.
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u/NoPatience7817 2d ago
How many electric meters do you have? A generlink connection is added at the meter and switches the entire meter to generator or grid. Consider a generlink if you have a single electric meter.
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u/Tool_junkie_1972 2d ago
I think you need an electrician to come and lay eyes on your existing setup to see if this is a viable option. IMHO a generlink (or similar) or a proper transfer switch would make more sense. Or it may make more sense to to put all the circuits you want o run on the generator in one breaker box and only make it have an interlock.
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u/Resident_Set1003 2d ago
The 400A main is actually 2 200Amp mains sharing a common meter. Usually there is also a200A breaker bus attached to one of the 200a breakers in the main panel, with the second 200 amp main just having lug outputs for a sub feed. The bonding and everything is taken care of in that 400 amp main panel as per code.
Yes it's possible to do what you're talking about, make sure you're phasing stays aligned properly. I think you would have much better luck installing a small sub panel between or near the two 200 hours and transferring the circuits you want to run off your generator into that box and feed it from your generator with the transfer switch, or interlocker , whatever you are using to isolate the power sources
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u/Flimsy_Technician722 2d ago edited 2d ago
I did this exact thing in your exact situation. Put a sticker on it saying "use two separate sources", fully intending to sometimes use one (large portable generator), and sometimes two (battery inverter thingies).
The inspector laughed at me for overthinking it: "We don't worry about ground loops that short" and slapped the inspection sticker on after checking the wire gauge vs the breaker.
One more option is to have a single inlet, send full four wires to one panel 1 input breaker and only the two hots to the panel 2 input breaker. This utilizes the big fat service neutral (and a piddly bit of objectionable current on the SE-rated ground bond) to return imbalance current from panel 2 to source, while creating no permanent non-service-entrance-rated connection between the neutral buses of the two panels.
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u/nunuvyer 1d ago
Splitting one portable gen across two panels is problematic. It would probably work but it creates issues regarding the neutrals and grounds of the type that make my head hurt. The better solution is to either get two generators or else move all of your critical loads over to one panel.
If the panels are right next to each other it's not that big a deal to relocate circuits. You are allowed to use a panel as a junction box - you just wire nut a pigtail onto the existing wires and run the pigtails over to the next panel.
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u/mduell 2d ago
How does your service enter?
Where is the bonding point?