Yikes, my first dreadful editing error. Meant to say:

My plan is to throw away (or hide...shh!) one of the three identical pullout switch blades ("C") such that only two of the three disconnects could ever be open closed.

use a transfer switch to power the whole 60 amp subpanel is my solution. To me it seems alot easier.

Uh, thanks Jason.

YOU CANNOT DO THIS WITH DISCONNECTS!!!!!
Don't even try!

You need a TRANSFER SWITCH at the 60A panel, between it and the main panel. Feed this also with the genset and be done. Since the shop is fed from this panel it will be powered as well.

The only problems is getting the feed from the genset to the transfer switch at the house.

I know you mean no harm, but the expense of a properly installed transfer switch is small change compared to the cost of legal fees in the event of an accident. Power Company attorneys would have a field day with your setup, and you should be prepared to write a big check if something goes wrong (even if you "know" it wasnÂt your fault). Many power companies would just cut your service entry down and come back (much) later if they observed such a setup.
It is a lot easier to prove in court that you had a transfer switch installed and inspected than it is to justify a clearly non-approved procedure that involves many steps and offers all types of opportunity for mistakes. The bottom line is that if you cannot afford or otherwise accomodate a transfer switch, you should not consider a "Rube Goldberg" set up to have "whole house" back up power. Buy some good extension cords instead.

Transfer switches are double throw (sometimes with an intermediate 'all off' position).
This is to eliminate ANY possibility of back feeding the POCO system.
The only other solution is the mechanical interlocking some panels have that moves breaker handles to open one when the other is closed.
No method that relies on anything else is acceptable.
In the dark, in a rush it is simply to easy to make a mistake.

Thank you, Petey Racer, for the advice.

I know that the single transfer switch between subpanel and main is the standard approach.

The only problems is getting the feed from the genset to the transfer switch at the house.

Yep, that's the biggest problem--and expense, too. That means digging a long trench, laying 100 feet of wire (at least 8-3 or 6-3) and the transfer switch. And it doesn't give me the option of using the outbuilding independently, without entering the house when it is shut down.

I've never seen a multi-way transfer switch, so perhaps there's no good, low-cost solution that meets all of my objectives.

Thanks!

I appreciate your thoughtful reply, Wayne.

I know you mean no harm...

You've got that right. In fact, I'm a whole lot more concerned about not causing an accident than I am about legal fees in the event of an accident. Heck, I don't want to fry some utility company lineman and I don't want to start a fire, either.

I don't see extension cords as an a decent option, given that I want to power the oil burner as well as a 15AMP 240VAC water pump, both of which are hard-wired to the box. Splicing BX cable with plugs seems even more "Rube Goldberg" than what I'm proposing, frankly.

But your legal warnings are still well taken.

Thanks.

I appreciate the details, brickeyee.

Transfer switches are double throw (sometimes with an intermediate 'all off' position).
This is to eliminate ANY possibility of back feeding the POCO system.

Agreed. Code notwithstanding, it still seems to me that I'd accomplish the same result with a procedure that required the blade be pulled from one of the panel disconnects in order to insert it into the generator disconnect. (Under normal conditions, there'd be no blade in that switch box.)

If you have a blade in your hand when you go to start the generator, you've disconnected one of the two panels and all upstream/downstream circuits that can possibly be connected to the generator, preventing backfeed to utility power. Inversely, if you have a blade to reconnect the subpanel or outbuilding panel, by definition the generator has been disconnected.

It can't be otherwise, can it?

In the dark, in a rush it is simply to easy to make a mistake.

I'm sure I'm being dense, but I'm not seeing the possibility for making a mistake here. That's why I wouldn't consider using disconnects without a removable enabling part. Without the requirement of physically transfering a part to complete the switchover, things could be done out of order with serious possible results.

I understand that transfer switches are double throw, but are they basic DPDTs (switching only the two hots) or must they guarantee isolation of the neutral as well? What's the effect, if any, of backfeed on the neutral?

Thanks again for the reply.

terribletom

Remember that when you sell your house you'll
have to make it code compliant at sale. (pay now or pay later)
Regards
Chris

In this case, making it code compliant in the event of a sale would take about 15 minutes and cost zero--nada.

Step 1. Remove generator plug, switch and about 6' of wiring. The other two disconnect switches can remain. (Tools required: screwdriver, pliers)

Step 2. Load generator on moving truck.

If you are using a portable generator (neutral and ground bonded at the generator), it is usually appropriate to switch the neutral. Ask your inspector or "authority having jurisdiction" (AHJ)to be sure.

I will say I have seen some methods similar to your own used with various results, some OK and some not. I'll also venture that no one "in the trade" is going to endorse the method you descibe, for reasons outlined above.

I cannot think of a handy and legal way to do what you want, given that you choose to leave the generator in your garage. Otherwise a transfer switch (or possibly a breaker interlock- I don't trust those) at your subpanel is the only code compliant way to power both locations.

It was kind of you to stop back in, Wayne. I appreciate your advice and feedback.

I'll also venture that no one "in the trade" is going to endorse the method you descibe, for reasons outlined above.

Nope, I wouldn't implement this plan if I had a license on the line either, if only because it is not code-approved. I expected the usual doctrinaire responses and only hoped that one or two folks might take some shots at the strawman on the basis of practical safety and viability. If the idea is flawed and dangerous, I definitely won't attempt it. If it's simply a departure from code, I might still think about it, but I'm nowhere near through thinking.

Opinion in this area of rural Maine is about equally divided about how to use a generator when the power goes out.

Half the folks trip their main breakers and plug their generators into dryer outlets. The other half hangs ratty 100' 18-guage extension cords out the window and have jury-rigged "plug in" furnaces. (I wasn't kidding when I mentioned putting a plug on BX cable. I've seen it.)

One guy I know put in a whole panel of three-way switches (the buck-a-piece 15A Leviton variety), each with one tail connected to a main panel breaker, the other tail connected to the generator, and the single feed going to a circuit. Why, it's a home-made 8-circuit transfer switch, right? (I gotta admit that I wouldn't want to sleep over at his house during a storm!)

But the one I really like (not) is the fellow who's identified two outlets on different poles, so he plugs one 120v generator feed into one house outlet, and the other 120v feed into the opposite-pole receptacle. That way, he's got whole-house 240 volt service, using two 18-guage extension cords. Ya gotta love that one.

Rumor has it that some guy down the road--a banker, I think--had a real honest-to-goodness transfer switch put in, but that's unconfirmed.

(I'm only half-kidding. But trust me, I'm not going to plug the thing into a dryer outlet or rely on an error-prone procedure that involves setting breakers and switches in the correct order. Fact is, I'd use a standard transfer switch at the subpanel if it did what I want to do without burying another fat wire to the outbuilding.)

Enough of my BS. Thanks for the good advice. Cheers!

p.s. I don't trust those breaker interlocks either, which raises another issue. I may be wrong, but I bet they don't prevent interconnection of the neutrals. Or do they?

All of the breaker interlock schemes I have seen did not switch the neutral. However, Square D did at one time make a three pole breaker that switched the neutral, and two of those should work with an interlock. I may still have one or two in the basement someplace.

I like that "banker" with the X-fer switch..LOL. Mine cost $100 from the "sidewalk sale" table at a nearby supply house. The manager nearly had a stroke when he found that someone (probably him) had mistaken it for a 200A disconnect.

"I understand that transfer switches are double throw, but are they basic DPDTs (switching only the two hots) or must they guarantee isolation of the neutral as well? What's the effect, if any, of backfeed on the neutral?"

because of the fact that it is a portable generator, you must have a 3-pole transfer switch to comply with code. the effect of not switching the neutral conductor is current flowing on all the grounded metal equipment in your home. portable generators are required to have a system bonding jumper (usually internal). that means that inside the generator the ground and neutral conductors are bonded together. now, keep in mind that this is also the case in your house (at the main). so, if the generator neutral is electrically connected to the house neutral, current returning along the branch circuit neutral conductors will split at the transfer switch. some current will continue to travel down the neutral conductor going to the generator like it is supposed to. however, some will travel down the neutral going to the main. once it get's to the main bonding jumper, it will travel back down the equipment grounding conductors to make it's way back to the genset's neutral. switching the grounded conductor as well as the ungrounded conductors alleviates this issue. it's a very dangerous situation so don't take it lightly :) and yes it is a code requirement, just in case you care. you brought up a good issue with the interlock kits. i'd be curious to find out.

"If you have a blade in your hand when you go to start the generator, you've disconnected one of the two panels and all upstream/downstream circuits that can possibly be connected to the generator, preventing backfeed to utility power."

You are the one being dense.
There is nothing to REQUIRE you to have ANYTHING "in your hand" when you start the generator.
The system has to be idiot proof with NO possibility of feeding back.

Your observations about breaker interlocks not switching neutrals is interesting. That's my impression too. I've only seen one that was installed, and that's my recollection too, looking back.

I'm not convinced that all the transfer switch "solutions" switch neutrals either. That's clearly a need for further research on my part.

Wow, did you ever get a great deal on that transfer switch. Congrats on that, and good eye!

Sounds like you're a good scrounger--something I definitely admire.

Best regards,

Tom

FWIW, not all generators require the neutral to be switched. only when a system bonding jumper is installed, which just happens to be mandatory for portable generators. when no system bonding jumper is installed, the problems i mentioned earlier are not present.

Wowzer, jmorrow, I'm blown away by your fantastic reply. I know you put some time into that, and I'm in your debt big time.

I agree 100% with your analysis and it parallels my thinking almost exactly. And I'm sure you'll understand, as well, why I see the problem of interplay between neutral and ground as being the real potential deal breaker in my so-called "scheme" (code notwithstanding).

[Among other things, if I have to switch three wires, that takes me out of the realm of those cheap two-pole air conditioner disconnects with removable blades. Maybe there's something like that designed for three-phase, but I doubt it'd be easy to find three identical ones at a reasonable price. Heh, the price of poker goes up.]

When I get to thinking hard about neutral/ground connectivity in a system with independent power sources, I wonder whether any of the so-called solutions truly isolate neutrals in a home-wiring environment.

Why? Because, ultimately, the equipment grounds end up connected--one way or the other. It seems to me that the two "ends" of the equipment grounds are inevitably bonded to: (1) the neutral in the main service and (2) the neutral in the generator. Isn't that true even if the neutrals are disconnected/switched?

If so, it doesn't mean that there's no value to switching the neutrals because electricity wants to take the "easy path". (That's analogous to the reason why subpanels should maintain separation.)

Furthermore, since portable generators bond neutrals and equipment grounds, I get what you mean about the potential for current-carrying neutrals flowing current back to grounded appliances, etc. But that's true with a transfer switch as well, no?

[The recommendation I've heard for using a portable generator to power house circuits is to remove the jumper and ground the generator to a local ground rod (reattaching the jumpers if the generator is used for standalone plug-in power at a job site, for example).]

Thank you very much for your insights, jmorrow. You've really helped me think this though.

- Tom

p.s. I am TerribleTom, after all, but perhaps I should point out that I'm not nearly as much of an NEC scofflaw as it might appear. In fact, the house in question is almost 200 years old and I've updated the wiring several times to keep at or close to current code. Last month, I put in AFCI breakers for the bedroom circuits even though the old breakers were grandfathered. Why? Because the code makes sense. So, yeah, I do care about code and, all other things being equal, I'll follow it every time.

Quote from Brickeyee:

You are the one being dense.
There is nothing to REQUIRE you to have ANYTHING "in your hand" when you start the generator.
The system has to be idiot proof with NO possibility of feeding back.

Thank you for your well-reasoned and helpful reply.

You are absolutely right. I'm the dense one because I can start the generator with nothing in my hand. But how, then, can I connect it to anything when it is wired to a removable-blade switch box with no blade? Trust me, I'm not going to stick my d**k into the hole.

You aren't getting it, are you? Think about it.

FWIW, not all generators require the neutral to be switched. only when a system bonding jumper is installed, which just happens to be mandatory for portable generators. when no system bonding jumper is installed, the problems i mentioned earlier are not present.

CAPISCE! "We cross-posted".

"You aren't getting it, are you? Think about it."

Tom, you are new here. Believe me, if there is ANYONE on this site who gets it, it's Brickeyee. There have been some other extremely knowledgable people chime in here, but Brickeyee not only knows code, but the engineering and science behind this.

It seems to me, just reading this, that you seem to want someone to say your idea is ok so you can proceed and feel good about it. Maybe?? Since deep down inside, you obviously know what is right, you should follow your conscience. After all, one of these times when the power fails, you might not be home and it will be some relative or neighbor who tries to energize the generator and causes a HUGE fubar for some poor lineman just trying to do his job. You would never forgive yourself. I'm not saying, I'm just saying....

Thanks, Cobra. Well taken.

And, in the interests of peace, tranquility and good feelings, my apologies to Brickeyee for the tone of my last reply to him.

If you disconnect the neutral (grounded conductor) you have a separately derived system.
Separately derived systems have grounding requirements similar to a service entrance.
The large systems (think 200 kW and up for large buildings) I install often switch all conductors and are designed as separately derived.
You are being your own little POCO at this point, but you cannot escape the NEC like the regular POCO does for distribution wiring.
The largest was over 2 MW. The transfer was accomplished on the 7.2 kV feeds to the structures primary transformers.

If you disconnect the neutral (grounded conductor) you have a separately derived system.

Nods. I agree with that assessment. Got me to worrying about continuity of EGs as well as neutrals, too.

While I'm still not convinced that my idea is actually any more dangerous or error prone than a couple of the "approved solutions" (maybe less so than some), I am pretty well convinced that it isn't wise to implement. (Hey, being right isn't always all it's cracked up to be, especially if you might happen to be wrong, eh?)

It took a bit of exhorting--not to mention a few incoming rotten tomatoes--but that's where I stand right now.

The large systems (think 200 kW and up for large buildings) I install often switch all conductors and are designed as separately derived.

Makes sense to me. I still wonder whether any of the residential systems truly separate grounding systems, what with things like pipes and fixtures being grounded and stuff like that, but I'll save that for someone who likes arguing about angels on the head of pins and arcane stuff like that.

You are being your own little POCO at this point, but you cannot escape the NEC like the regular POCO does for distribution wiring.

LOL, agreed.

The largest was over 2 MW. The transfer was accomplished on the 7.2 kV feeds to the structures primary transformers.

Well, that's at least 1.994 MW out of my league!

Thank you, sir.

Back to the OPs original question. You can accomplish what you wish, with code compliance if you implement 2 automatic transfer switches. For the small loads you are talking about small ATS are not that expensive. In the 30 and 50 amp range they are plentiful in the RV industry and are UL labeled and meet the requirements for permanent installation.

None of the smaller ATS that I have seen for home or RV use switch the neutral and are intended for permanently installed gen sets.

Wow, that's exciting, and I appreciate your stopping in.

I wish I had a clue about how to do this with the two ATS's. Is there really a way to reuse the house-to-building cable as a backfeed with low-cost x-fer switches?

I'm all ears.

Thanking your in advance--

Tom

You would still have to run a 14/2 between the ATS at the main panel and the ATS at the sub panel for the utility sensing line. I did not think the solution through. Usually the auto transfer switch sensing line is internal to the switch housing, would be remote in this instance.

Sorry for the confusion.

Hey, no prob at all! Thanks for stopping in and following up...an extra mind is always welcome when thinking through a problem.