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Generator Transfer Switch

Posted by jsimon7777 (My Page) on
Fri, Mar 9, 12 at 14:53

I have what may be a complex installation for a home transfer switch. The generator is a Yamaha YG6600DE, a contractor-class model. I think it can work at its rated capacity all day long.

Here is a diagram of the system. Currently there are three buildings and six electrical boxes! The blue parts are parts I'd change and add. The idea is to disconnect the wires from the main breaker and plug them into the outlet of the transfer switch. Then connect new wires to the main breaker from the transfer switch. Then connect new wires from the generator to the other end of the transfer switch. That way, there'll be no dead linemen, and I can run my lights, gate, well pump, and water heater (alternating between the water heater and well pump).

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Here is the PGE panel with the maim breaker panel closed.

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Here is the main breaker below it, 175amp.

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Inside the main breaker panel. The wires go through to a patch box I'll show later. I think the white wire going down from the bus bar is ground. I think the black wire coming out of the hole to a bus bar is ground from the rest of the system.

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A closeup of the bus bar and where the PGE service comes in from the Smart Meter.

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Now we're looking along the wall behind the main. The wall is to the left. The main breaker is right behind it. Below the hunk of wood in the center is metal conduit that comes out the back of the breaker box, where the three big wires go.

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The splice box where magic happens. I think two wires come from the house, two from the garage, three from the main breaker panel, and three from the well house panel above the splice box.

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The insides of the Federal Electric panel in the well house. I get the feeling I should replace it. Notice the three massive black wires feeding it. Notice the crazy turn the far left wire makes. Also notice how all three big wires come from the conduit that leads to the splice box below.

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Is this design general design acceptable? Should I ground the generator? It's manual says to, but ground confuses me. The generator does have it's own GFCI.

I'm thinking of replacing the Federal box while I'm at it. I could also replace the main breaker box and Federal panel with a single panel, but then I'll have to go diving into the scary splice box, get PGE to shut off service, and hire an electrician. As it stands, my buddies, two HVAC guys who have to do other types of electrical wiring all the time, should be able to handle this.


Follow-Up Postings:

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RE: Generator Transfer Switch

Of course I'd love to just put in an interlock or something simple, but the well is on one panel, the water heater is on another, and the garage door is on another. I'm not sure which one feeds the gate, but I am sure that this is the only way to get generator power to all the needed places.

Might I be able to add a transfer switch inside the main breaker box? That might simplify things. Otherwise I'll have to splice to the two wires currently coming off the breaker because they won't be long enough to reach a transfer switch.


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RE: Generator Transfer Switch

1. In that first box with the 175a breaker, the black wire with the white tape on it is Neutral. The White wire is probably a ground (very probably), but you should see where it goes anyway. I would put green tape on it, but that's just me.
2. what you're asking to do is to set up a generator inlet do power your whole house. By code (I think), this generator would need to be something like 42Kw.
3. where do you plan on placing the generator?
4. code varies from place to place. Some would require you to put in a large generator if you were powering the whole house. Code (or the AHJ) would require you to put in a subpanel containing the circuits that you want to power during generator operation. But obviously there are people that don't do that and have a similar situation as you.
5. I'd rather let a real electrician comment on this, but I think you should be able to place a transfer switch and generator inlet next to the box under the meter and be able to hook it up.


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RE: Generator Transfer Switch

If I had to wire into specific circuits, because the various pieces are spread out, I'd be looking at making several runs of new wires over hundreds of feet, or having multiple generators at different locations. That is unrealistic.

A 42Kw generator would be nice, but I just want to hobble by with lights, the fridge, hot water, the well, and the gate working. It would be massive overkill. Oddly enough, used generators in that size range aren't that much more expensive than the small ones, but if I had a 42Kw diesel, I'd be constantly wet stacking.

Our typical house load is about 2Kw per hour, with the heaviest hours at about 6Kw per hour. Sure, if the stove, water heater, pump, house heater, and microwave are all on at once, we'd blow past that. However, in typical situations, we're looking at a 1.5Kw base load (lights, fridge, PC, etc), another 1Kw for the pump when running, and another 4800Kw for the water heater when running.

I'm thinking of placing the generator near the propane tank, about 30 feet from the house and about 50 feet from that panel. We'd run conduit underground then up that wall, using wire appropriate to a ~50amp load. House the generator in a lean-to or box to keep it dry, with the exhaust running out and a fan blowing to cool it.

The more I deal with code, the more I think it's stupid much of the time. It's a bureaucrat's dream.


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RE: Generator Transfer Switch

You can feed the whole house with a smaller generator but NOT one with an automatic transfer. You absolutely MUST have a proper transfer switch / interlock.

Yes the generator must be grounded. Once you are past the 175Main, all the grounds and neutrals must be separated.

Sorry, the CODE is there for occupant and fire safety. It is not just bureaucracy. Most people who believe such are ill-advised to design and install their own equipment as they do not understand the issues involved.


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RE: Generator Transfer Switch

ronnatalie,

Thanks for your feedback.

Are you saying that this setup, with a manual switch, will work and be proper?

I think safety should be balanced with other concerns, not held on a pedestal or thrown out. For instance, I'm backfeeding through the dryer's outlet, and I am going to use a transfer switch. I'm also talking thinking about replacing that Federal panel. The code makes life difficult and expensive for everyone with an older house.


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RE: Generator Transfer Switch

Sorrry, if you are gong to insult me and insist on doing illegal and dangerous things both to you, your family, and the public at large, WE CAN NOT HELP YOU.

If you are willing to learn how to do it in the safe and legal fashion, we can.


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RE: Generator Transfer Switch

ronnatalie,

Sorry, I wasn't aware that I insulted you. I'm not sure what insulted you, but I didn't mean to. I do have problems with the code and laws surrounding it, but that's not you. It's not just the electrical code, either. The whole mess of laws is insane. We regulate home owners up the wazoo while Wall Street ruins the economy, takes the money, and runs to Monaco.

You seem to be saying that my design has something that's not safe, and I'm trying to figure out what that is.

You said a manual transfer switch, which I agreed with and already planned for. You said to ground the generator, which I had asked about but wasn't sure as I'd read posts against adding grounds in different areas.

Then you made a comment about the 175 main and keeping everything separated. This I'm confused by. Would the transfer switch have to go between the breaker and the Smart Meter? I shudder to think of how many amps the transfer switch would have to be built to take since it won't be protected by a breaker. Would I need a transfer switch that handles three different 00 or 000 lines at once? Does such a thing even exist?

Or are you saying that every single circuit that the generators will run will need to have a second run that goes to the generator and has a cut-over to the generator's circuit in case of a power failure? That doesn't seem right and I don't think you meant that, but I'm not sure. It would be prohibitively expensive.

As far as hiring an electrician for this goes, the last one I hired ruined the main panel of our rental. The one before that did clever things like not bother with sealing conduit entries into the house. Considering they're typically 120-150 an hour in these parts, I'm not a huge fan.


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RE: Generator Transfer Switch

I have no idea what you are talking about, but when I bring up code issues and you tell me they're nothing but bureaucracy, and I tell you how to do it right with a proper transfer switch and you say you're going to back feed through a dryer outlet, what on earth am I to do with you?

No the transfer switch goes where you've drawn it, and if it is indeed a transfer switch it needs to switch the entire 175A load. If by transfer switch you're talking bout one of these units that has a sub panel attached (probably your best bet) then it only needs to be sized to the loads you are moving to it.

My comment on separation is that your service disconnect is the 175A panel on the meter. THat is the only place ground and neutral should be connected. You need to keep those separate through the transfer switch (and hopefully tho sis already in place) the other subpanels and the generator.


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RE: Generator Transfer Switch

Hehehe. I just reread. Backfeeding through the dryer was a mistake. I missed the NOT when I typed it. Oops!

>>>I am NOT backfeeding through the dryer.<<<

I AM using a transfer switch. Sorry for the mistake. Now I get the confusion. My apologies.

OK, I if I leave ground in place on the main breaker panel and run the neutral through the transfer switch THEN to its current position on the main panel, I will successfully keep them separated while not killing a lineman, yes? No fires or danger? The generator will have its own ground stake from the frame. I was thinking of using a GE TC10324R or similar. http://www.homedepot.com/buy/electrical-breakers-distribution-load-centers-safety-switches/ge-200-amp-emergency-power-transfer-switch-175644.html

I will have to manually make sure that no two large loads are running at once. Short of buying a 70Kw generator, I think this is all I can do.

A neighbor works for an electrical supply house so I will go with what transfer switch he suggests.


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RE: Generator Transfer Switch

Yes, as long as the transfer switch has an electrical or mechanical interlock to keep the generator from back feeding the lines, that protects the outside (and also keeps them from "retaliating" on you).

For your own safety, you need to make sure that other than the service disconnect (which appears to be the 175A panel at the meter in your case) that all your neutrals and grounds remain separated. This was a requirement for the subpanels even without the generator, but I've seen even experienced electricians get loopy around transfer switches and fail to do it right.

As stated before, the smaller generator (and you want to use a proper inlet connector if it is cord connected....i.e., with no exposed powered pins.).
But as alluded to earlier, the code allows you to use a smaller than full sized generator on a manual transfer as they figure you'd be smart enough to shed the load manually before throwing the transfer.


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RE: Generator Transfer Switch

Thank you!


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RE: Generator Transfer Switch

In addition, you should go to each of the panels/subpanels and mark which circuits should be on and which should be off during generator operation. You should think about placing visible instructions on the panels so that any one can understand how things have to be set prior to activating the generator.


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RE: Generator Transfer Switch

1. I see from your schematic that you are planning to switch the neutral conductor. That is good, because the if you dont, the GFCI on that yamaha will trip the second you try to use it. And yes, they do make a switch that will do that (think three phase).It also looks like you will need a seperate ground wire from the main breaker (service disconnect) to the switch and from the switch to the various panels.

2. When you open up those splices in the splice box, get rid of those split bolt connectors and go with "polaris connectors" they are much better and easier to use.

3. Get rid of that FPE panel yesterday. Im suprised it hasnt burned up the place already.

4. Ronk makes good transfer switches, check them out.


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RE: Generator Transfer Switch

Hi Auger,

1. The GE switch has two wires and a ground that go through it. The two wires are broken when the switch is thrown, but the ground is not. Will that trip GFI or must I go with a unit that breaks ground too?
https://images.tradeservice.com/OMHPCVA38H2GOHK7/ATTACHMENTS/DIR100004/GENELEC00006_2_7_2_17.pdf has the specs for the unit. I also notice that the unit is only designed for 6awg and smaller. I know the wires are 00 or 000, so how can I safely connect them? It's weird that it would be a 200amp rated switch, but only can take ~50amp rated wire. Am I missing something?

2. My hope was to not go into the splice box since they're all spliced into three wires that come out to the 175 amp main. Are you saying I should be going in there? Why?

3. I hear ya. It will get changed out the same time the transfer switch is put in.

4. I see that Ronk has switches that take 00 and 000 wire. They're a bit more expensive, but not ridiculously so. Thanks for the recommendation.


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RE: Generator Transfer Switch

Since there has been changes to the Electircal code since your house was built, if you change anything, you have to bring what you change up to the current code.

Current code requires a neutral wire as well as a SEPERATE ground wire after the main breaker panel. This would make a total of four wires running to and from your transfer switch to the various panels. I know that is going to be hard to do with your current setup, but it is what it is.

In order for that generator to work properly, yes, you will need to also switch the neutral as well as the two hots. If you dont, the GFCI will trip. The ground is never switched. You could use a two pole switch IF you modified the generator intenally, but if you did that, the generator wouldnt work properly unless it was hooked up to your house.

2. I just assumed you were going to go into the splice box because the diagram shows new connections there. You dont have to do that way.


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RE: Generator Transfer Switch

I don't know how old that house is, but the code has required separate grounds and neutrals for the entire 30+ years I've been in the business.


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RE: Generator Transfer Switch

House was built in the '60s.

Currently, the house, garage, and well house go into the splice box. Then three black wires come out of the splice box into the main breaker panel. One black wire goes up to a bar in the upper right of the main breaker panel. A white wire that I assume is ground then comes down and goes into a pipe that leads to the ground. The other two black wires that come out of the splice box go straight into the bottom of the main breaker.

That leaves me, as far as I can tell, with three wires from the splice box that I should deal with. I reroute the three black wires to a 3-pole transfer switch then add new matching wires from the transfer switch to the main breaker and the bar. I leave the white ground wire where it is. I hook up three wires from the 240V generator to the transfer switch. The fourth wire from the generator (4 wire plug) goes to the bar in the main breaker box because that connects to ground.


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