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Old 10-22-2012, 01:13 PM   #1
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Hookup..Generator transfer switch to main & sub panel


I'm hooking up a Reliance 6 circuit transfer switch....there is only one question
I'm not sure of.

Four of the circuits i want to use with this switch are in the main service panel, the other two circuits are in a small sub panel next to the main. Does
the fact that the ground and neutral wires share a common buss in the main
panel, but are isolated in the sub panel cause any problems? I'm hooking the
ground and neutral wires from the transfer switch to ground and neutral buss in the main panel.

Thanks in advance for any help.
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Old 10-22-2012, 08:17 PM   #2
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Hookup..Generator transfer switch to main & sub panel


Does not make any difference.

The hot wires of the cables of the branch circuits eligible to receive generator power are removed from their respective panel breakers and connected directly to or pigtailed to the wires coming into the panel from the transfer switch box.

Additional wires from the transfer switch box are connected to the breakers from which the various branch circuit wires were removed.

The neutral wires of the cables of those eligible branch circuits remain attached to the panel neutral busses as-is.

When utility power is in effect, the power comes from the panel breaker, goes out to the transfer switch box via an individual wire for that branch circuit, comes back into the panel, and feeds the circuit cable. The power returns on the circuit neutral to the neutral bus and returns to the pole transformer. When utility power is in effect, the individual transfer switches in that box behave like switch loops whose loads are the respective branch circuits.

When generator power is in effect, power goes to the transfer switch box via the generator inlet, and into the panel via the individual wire for that branch circuit, skipping the panel breaker and feeding the circuit. Power returns via the circuit neutral to the panel neutral bus and out the transfer switch neutral you attached to the neutral bus, and back to the generator. For a circuit whose breaker is in the subpanel, the return current goes from the subpanel neutral bus to the main panel neutral bus to get to the transfer switch neutral.
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Last edited by AllanJ; 10-23-2012 at 05:57 AM.
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Old 10-23-2012, 10:36 AM   #3
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Hookup..Generator transfer switch to main & sub panel


Quote:
Originally Posted by AllanJ View Post
Does not make any difference.

The hot wires of the cables of the branch circuits eligible to receive generator power are removed from their respective panel breakers and connected directly to or pigtailed to the wires coming into the panel from the transfer switch box.

Additional wires from the transfer switch box are connected to the breakers from which the various branch circuit wires were removed.

The neutral wires of the cables of those eligible branch circuits remain attached to the panel neutral busses as-is.

When utility power is in effect, the power comes from the panel breaker, goes out to the transfer switch box via an individual wire for that branch circuit, comes back into the panel, and feeds the circuit cable. The power returns on the circuit neutral to the neutral bus and returns to the pole transformer. When utility power is in effect, the individual transfer switches in that box behave like switch loops whose loads are the respective branch circuits.

When generator power is in effect, power goes to the transfer switch box via the generator inlet, and into the panel via the individual wire for that branch circuit, skipping the panel breaker and feeding the circuit. Power returns via the circuit neutral to the panel neutral bus and out the transfer switch neutral you attached to the neutral bus, and back to the generator. For a circuit whose breaker is in the subpanel, the return current goes from the subpanel neutral bus to the main panel neutral bus to get to the transfer switch neutral.
Thanks so much for your reply. I guess I was over thinking the problem.

Now I know I won't burn down the house....
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Old 10-29-2012, 09:51 PM   #4
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Hookup..Generator transfer switch to main & sub panel


I have the same problem. Also, the leads from the transfer switch are too short to reach the sub panel circuits. What is the proper method of lengthening the leads to reach the sub panel circuits?
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Old 11-05-2012, 11:10 AM   #5
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Hookup..Generator transfer switch to main & sub panel


Hello all,
This is my first post, and only because I am not able to locate voltage information on a/c, forced air heating and water heater. I live in East Stroudsburg, Pa.

MY PLAN:
Connect a transfer box to cover the following items in the breaker box:
Breaker Label Breaker Size
1. outside a/c unit 30/30
2. water heater 30/30
3. master bedroom 15
4. master bathroom 15
5. sump pump 20
6. parlor and tv/dish box 15
7. refrigerator 20
8. Hood/Range 20

I have propane and force air heating. A/C will be switched with Heating in summer. I am considering a 10 switch transfer box, and my question is what size generator would I need for this setup? I have a Champion Power Equipment 41135, 5500 running watts/6800 starting watts generator, will that work?

I am comfortable in myself to tackle the installation of the switch, I'm not an electrician by any means. I have done minor electrical work and have never taken a shock, but when it comes to volts, watts and amps, I say What? Thanks for any help here!!!!!
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Old 11-05-2012, 01:01 PM   #6
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Hookup..Generator transfer switch to main & sub panel


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I have a Champion Power Equipment 41135, 5500 running watts/6800 starting watts generator, will that work?
That generator is not large enough for your loads. The biggest problem is the air conditioner. Even with no other loads, a 5500/6800 generator might not be able to start your AC compressor. Now if the AC kicks on while the hot water heating elements are on or you have a hair dryer going, it has little chance of doing anything except tripping the circuit breaker on the generator or damaging your appliances.

I think you should reconsider what loads are essential to you or purchase a significantly larger generator. $0.02.
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Old 11-05-2012, 01:22 PM   #7
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Hookup..Generator transfer switch to main & sub panel


"I think you should reconsider what loads are essential to you or purchase a significantly larger generator. $0.02. "

jeffsw6, Thank for the reply, and your 2 cents will beat my dollar every time. What size generator would you recommend. I hope I can make it through this winter with this generator, no a/c needed, hood/range can be lit by lighter.
How would you handle this if it were you?
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Old 11-05-2012, 01:45 PM   #8
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Hookup..Generator transfer switch to main & sub panel


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How would you handle this if it were you?
Honestly I think your biggest problem during winter is the blower for your propane-fired heater. If you don't have power for the heat, you had better get some electric blankets or abandon your house until the utility power comes back on, right?

Once you know what loads are essential vs what loads are conveniences, then you can decide if you are willing to spend that much money on a generator for the essentials or a little more for the TVs and satellite boxes. When you think about it, a home generator, transfer panel, and fuel storage can easily cost more than staying in a hotel (if there is one nearby with empty rooms) for several weeks. However, having power for your sump pump is really essential, and the same might be true of your refrigerator if you have a lot of valuable meat saved from hunting, etc.

So think about the economics of it. I would not buy a generator smaller than 20kW for a transfer switch setup. It just doesn't make sense to risk damaging your appliances if the generator bogs down when a big load kicks on -- and insurance will not cover damage you do to your own appliances with your own generator!

This will go against what most people say about the safety of running extension cords around your home, but me personally, I have a 6500w generator and if the power goes out during winter, I run a couple of 10/3 extension cords so I can power my refrigerator in the kitchen, electric blanket and space heater in the living room, television, and my second refrigerator in the garage. The reason I use 10/3 is less voltage drop from the generator (outside) to my loads. I got 100ft 10/3 cords for about $70ea at Harbor Freight with a 20% off coupon from the newspaper.

If I really wanted to I could hook my hot water heater to the 30A 125/250V receptacle on my generator. But honestly, if my power is out so long I can't go another day without a hot shower, I'll go shower at a friend or relative's house or rent a hotel room.

That's my economical home generator setup. It's the bare essentials and it's all anyone should really do, in my $0.02 opinion, unless they are willing to spend enough to have the right sized generator for all the things they really want to run, as well as a safe transfer switch and sub-panel for their generator-protected loads.

Remember to plan for where your generator will be located during the power outage you are planning for. I know someone whose generator was stolen WHILE IT WAS RUNNING right out of his driveway. Someone just ripped all the cords out, tossed it in their truck, and sped off, didn't even bother to stop the generator engine. If you live in an area where someone might take a portable generator, come up with a way to chain it down. Make sure the exhaust gases are blowing away from your house, not toward it. Never run a generator inside your garage. Blablah.

I hope this is helpful. I think you and I are in the same boat -- we don't want to spend a fortune on a generator but we know the utility companies are doing a bad job of getting power back on after storms these days. My plan worked out well for me during 2 storms so far. Electric blankets are great, they hardly use any power to keep you warm enough to stick it out in your house until things return to normal.
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Old 11-05-2012, 02:09 PM   #9
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Hookup..Generator transfer switch to main & sub panel


I didn't even consider electric blankets, lol!!! Sounds like a solid plan to consider. Closest relative about 1 1/2 hrs away, same for work but a different direction. Thanks for the insight!!!!
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