View Full Version : Wiring a generator to two panels
bikerart
Oct 6, 2009, 11:20 PM
I have 2 200 AMP panels. I would like to know how I should hook the second panel. I already have the first one wired in.
Thanks for looking.
Bikerart
tkrussell
Oct 7, 2009, 02:47 AM
Can you provide some photos of the open panels and show how the first panel is wired to the genset? That would help, as there are various mechanical methods to deal with the various wiring methods.
stanfortyman
Oct 7, 2009, 04:04 AM
I have 2 200 AMP panels. I would like to know how I should hook the second panel. I already have the first one wired in.
Thanks for looking.
BikerartThis is near impossible without a 400A transfer switch. So if you have a 200A transfer switch on one panel right now you'd be looking at several thousand dollars just in material alone.
Most times we just put all critical/wanted loads in one panel and do the same as you have.
medic-dan
Oct 7, 2009, 08:19 AM
How about put in a subpanel off one panel just for the generator loads?
stanfortyman
Oct 7, 2009, 03:42 PM
How about put in a subpanel off of one panel just for the generator loads?
He already has one 200A panel wired to a transfer switch.
bikerart
Oct 7, 2009, 09:00 PM
There actually isn't a transfer switch. I have the box that the generator plugs in to and that goes directly to a dual 30 amp fuse on the first panel. I have been told I can run another line to the second panel the same way as the first panel. When the power goes out I will go down and switch off the 2 200anp main breakers then start the generator and then plug it into the box. Only after that is done I will switch both of the 30 amp breakers on. Does this sound good? I believe the 2 30 amp breakers are in parallel not in series, right? This should not load anything down more that necessary.
bikerart
Oct 7, 2009, 09:01 PM
I guess my post before my previous one did not make it on.
medic-dan
Oct 7, 2009, 09:40 PM
So you have an interlock on the first panel to keep you from backfeeding and you want to do the same to the other panel and run both off the same 30a generator feed?
tkrussell
Oct 8, 2009, 02:45 AM
This is why I asked for photos, to prevent any guessing and endless posts.
bikerart
Oct 8, 2009, 10:43 AM
OK finally got the pic of the panels. The input cable is in the lower right corner of the right side panel. Sorry for the delay, in the middle of painting the house and building a bike.
Bikerart
medic-dan
Oct 8, 2009, 11:23 AM
Where is the generator connection on the first panel? How'd you bring it to the second?
What's that cable in the middle of the right panel going to the double breaker?
What kind of interlock are you using? You are using an interlock aren't you?
bikerart
Oct 8, 2009, 11:51 AM
The generator connection is from the 10/4 cable in the lower right on the right panel it connects to a dual 30 amp breaker. Not shown in the pic. But that is how I worked it last winter on just the right panel. That double you ask about is my furnace breaker. No interlock. I plan on doing a dual connection at the box outsit where the generator plugs in and running another 10/4 to the second panel.
KISS
Oct 8, 2009, 12:09 PM
1st strike: No interlock kit. See www.interlockkits.com
This would interlock the main breaker with the generator input.
A solution:
Buy an interlock kit for BOTH panels.
Feed panel #1 from generator input interlocked breaker (G1/M1).
Put another breaker in panel #1 (Gx1); 30 A. This will be your feed to panel #2.
Put a 30 A breaker in panel #2 interlocked to the main breaker in panel #2. (M2/Gx2)
Just naming breakers: M1, M2 = mains; G1, G2 are interlocked
Gx is a xfer breaker.
So to use the generator, turn all loads and main off.
Turn on G1 (can because M1 is off)
Turn on G2( can because M2 is off)
Turn on Gx (Gx can be on all the time)
Now main panel 1 is fed from main panel 2, via Gx and G2 and generator is fed interlocked to main panel #1.
Now everyone should be happy. The AHJ, the lineman and the power company. Your pockets might be a little lighter.
Some panel manufacturer's have interlock kits designed for their panel.
Where does the big green wire go on the left panel?
tk:
I think we have a ground loop issue here with the main ground.
tkrussell
Oct 8, 2009, 12:45 PM
Kiss I think I see what you see. I don't see a problem right off, let me explain why:
The large 2/0 ish green in the left panel probably is the grounding electrode conductor, and then a jumper to the next panel, since the Main Breakers are in the panels.
I would have grounded my neutral at the meter, and not need the jumper.
Not the way I would do it, but hey, the service has been installed, inspected I assumed, and connected.
You already took care of the genset connection.
Bike, the generator power feed entering the panel will get a proper connector, right?
And follow Kiss's advice, get interlocks on both panels.
KISS
Oct 8, 2009, 01:13 PM
Tk:
The neutral bar looks bonded to the case by the green screw. It would seem that you would want to have separate grounds and neutrals in the right box and remove the neutral lug.
Otherwise, you have a ground loop and any main neutral current on the right box will try to be dropped across the copper interconnectng wire.
So, proposing:
Left panel the neutral is grounded with the bonding screw and grounds and neutrals are the same.
The second panel be treated as a sub-panel where ground and neutral remain separate and independent. Neutrals and grounds should go to their respective busses.
tkrussell
Oct 8, 2009, 04:01 PM
Since the Main Breakers are in these panels, the neutrals in both panels must be bonded to the equipment ground, just like in the photo.
It is wired correctly.
stanfortyman
Oct 8, 2009, 06:02 PM
The generator connection is from the 10/4 cable in the lower right on the right panel it connects to a dual 30 amp breaker. Not shown in the pic. But that is how I worked it last winter on just the right panel. That double you ask about is my furnace breaker. No interlock. I plan on doing a dual connection at the box outsit where the generator plugs in and running another 10/4 to the second panel.
PLEASE DO NOT do this any more. You have been lucky so far that you have not killed anyone. YES, it is quite possible to do, and if you get caught without a transfer switch or interlock you could face fines or worse.
PLEASE listen to the others and get some kind of transfer switches or interlocks on those panels!!