Backfeed generator through dryer outlet?

[Steve Spence]

The relay on the left switches the neutral, the relay on the right switches both hots. they are interlocked.

[daestrom]

Regardless. If my installation allowed my wife/adult-son to energize a line from the home generator because I didn't bother installing a positive disconnect, and it killed an over-worked, tired lineman who missed one step in his safety procedures, the guy is still dead. Or some stranger touched a down line at an accident scene, that was supposedly switched off by the utility but wasn't actually de-energized yet because of my generator, they are still dead.

And regardless of lawyers, wrongful death suits, contributing factors, or any other 'paper excuse', someone ending up dead because I skimped on a safety feature, isn't going to help me sleep at night.

Some of us care more for our fellow man than to just say, "Well, they obviously didn't follow procedures", or "Another candidate for a Darwin award." Maybe you should go tell the widow of a dead lineman who was working for 20 hours trying to get people their power back, how it's obviously her spouse's fault that he's dead. Or the widow of the rescue squad guy that touched a live wire after the utility folks pulled all the fuses, trying to save someone else's life that they deserve the "Darwin Award" for the year.

daestrom

[daestrom]

And that inexpensive little link bar is too much trouble to install?

FYI, tags alone don't meet the OSHA requirements for tag-out/lock-out in residential setting. Tag-out only works if all employees/personel that have access to the area receive basic tag-out training. Otherwise, locks are required.

But that's OSHA. I'm sure you'll argue that such rules don't apply in an emergency (except to the lineman that forgets a step in their procedure and ends up dead). BTW, is powering up your home to save $200 of beef in the freezer, or watch TV an 'emergency'??

daestrom

[Pete C.]

I'm single, the switch gear is under control of a single competent person.

The main breaker *is* a positive disconnect. It is not mechanically or electrically interlocked with the other breaker however.

Well, I'm not as concerned with avoiding enabling other people to injure themselves. Every time you drive your car you are also enabling other people to injure themselves and are relying on them to follow procedures such as crosswalks and traffic lights to prevent them from being injured by your car.

If you have sleep issues they have medication for that.

Life is full of risks and as they say "They knew the job was dangerous when they took it". While I'd not be quite so blunt with that widow(er), the bottom line is that the person in question knew they were taking a risk by working excessive hours or short cutting procedures and the ultimate responsibility for the results of that risk land on their shoulders. I enable them to kill themselves every day by simply funding the power utility.

Pete C.

[Pete C.]

What happens if a coil burns out on one of the contactors? One side switches and the other does not, you could end up with a situation where you have lost your neutral, i.e. hots from one source and neutral from the other source. Could be ugly.

On the transfer switch I built I had a solid neutral, but only used the NO main contacts on the contactors. If a contactor coil were to fail I would not have a situation where I lost a neutral or a phase. The NC auxiliary contact blocks on the contactors were used to provide the interlock to prevent any possibility that both contactors could be energized at the same time. It would require two failures for that to occur, both the upstream control to try to energize both contactors and the failure of one of the aux contacts to allow it to actually happen.

Pete C.

[Pete C.]

Depends, as long as you have adequate panel space then it's not too much trouble. The mechanical link bar kits require the breakers to be positioned opposite each other so you can't use the standard top center main breaker position. Since the link bar requires one of the breakers to be off at all times that means you have to have a dedicated back feed circuit.

Ultimately you need four panel spaces for the two breakers and need to install a dedicated back feed outlet. Still a cheaper and easier option than any of the standalone transfer switches. Likely something I will do when I replace the POS Stab-Loc panel in my current house with a decent

40 space QO panel.

Actually OSHA rules don't apply at all in a non-commercial setting. OSHA only applies to commercial contractors working in a residential setting, not to homeowners.

Depends on the situation and it's not as clear cut as you might think.

In most circumstances it probably doesn't qualify as an actual emergency, more of an urgent property protection situation. However consider the case where you live in the boonies and are getting the

100yr blizzard of doom. In that situation where you may well not be able to reach a store for days or weeks, preserving your food supplies and watching TV for news reports and info would certainly qualify as an emergency.

Pete C.

[JoeSixPack]

You know nothing of who I am, and are quite mistaken.

[Antipodean Bucket Farmer]

Arguing about the details on Usenet is easy. But, even if you are technically "right," (and, legally, that might not be good enough), would you really want to risk arguing the matter in court, AFTER someone has died, and the utility and that court are looking to punish someone?

[Pete C.]

Let's not get into the corrupt and bogus legal system...

Pete C.

[JoeSixPack]

Do you think you might lose a limb or something if you concede that you may not win this argument?

[Pete C.]

The fact remains that there have to be additional failures beyond back feeding for a lineman to be killed.

Pete C.

[gfretwell]

The short answer is if the generator has the neutral bonded to the frame (equipment ground) the transfer equipment will have to switch the neutral. You can't have 2 bonding jumpers in one system, switching the neutral isolates one of them.

Look at "separately derived systems" in the NEC art 250

[Me]

If the coil fails, most contactors will be unenergized and that makes the contacts OPEN in most cases. This is standard for MOST electrical systems design. You design the system so that if therer is a failure, It is in the unenergized way and all contactors are OPEN.....

Me

[Me]

Square D makes them in various sizes. Most folks just get a 3Phase Transfer Switch and use the third set of contacts for the Neutral. Two Hots and a Neutral, all switched.......

Me

[Waldo]

Here's another one for you -

Federal Pioneer (Canadian division) GP3P60-20

60 Amp, 1 Phase, 3 Wire

[Pete C.]

Right and that was my point and also the way I designed my electrically interlocked transfer switch using only the NO contacts on the contactors and one contactor per source.

In the RV style auto transfer switches I've seen that use DPDT relays, they use a single DPDT relay and switch either a 120V source with neutral, or a 240V source with a solid neutral. A relay coil failure will leave you stuck on one source but will not create a hazardous situation.

The transfer switch as described by Steve appears to be using two DPDT relays to emulate a 4PDT relay with one source on the NO contacts and the other on the NC contacts, the common feeding the load. With one relay you are safe, but with two relays a failure of one will put you in a half switched state which could be hazardous.

Steve stated that the relay on the left was switching the neutral and the relay on the right was switching the two hot legs of the 240V feeds. If one of these relays were to fail you would get the two hot legs from one source and the neutral for the other source which could certainly cause significant problems.

My recommendation is that Steve review carefully the "what if" scenarios for the cases of the failure of either relay. I think a safer route would be to locate a suitable 3PDT or 4PDT contactor to replace the two relays or to go with a solid neutral.

Pete C.

[Solar Flare]

Exactly! but it is never a good idea. Do it safely like a real man, with a transfer switch.

[Solar Flare]

[Pop]

LOL! If nothing else, this set of threads has presented an excellent who's who for the plonk list! I haven't seen this much silliness since, well, ever, actually!

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[Pete C.]

Er, like what? The way Steve apparently has it currently?

Pete C.