As I said earlier I am being inundated with generator questions here lately.

Here is an interesting one. Can a snap switch be "transfer equipment" as in, can they have a box on a piece of equipment with a double throw switch that switches the load between the generator, via an inlet for a temporary cord and the utility? I don't see a safety issue but there might be a code/listing issue.

I already said no on simply pig tailing out a cord and cap from the box.

Is this switch still a disconnect? (with no cord plugged in)

Greg,

Are you talking about a 3 position disconnect that is set up for Utility, OFF, and Generator? I have seen that setup in a former dairy barn.

Nope they are asking about using a box with a 5-15 inlet connector and a SPDT snap switch to switch a 120v line.
The generator is set up as an SDS (neutral bonded)

Single family dwelling if that matters.

They assume most of the loads will be C&P connected. This is for a well pump but I did have the same question asked from someone up in the frozen north who wanted to do the same thing with a (gas) furnace blower.

I suppose if you used a center off snap switch it solves the disconnect problem but is it legally "transfer equipment"

Greg,

Snap switches are not listed by UL for the use that you describe. See SNAP SWITCHES (WJQR) in your White Book. "Snap switches have not been investigated for switching a load between two alternate sources of supply."

Tom

Thanks Tom. That is the answer I needed.
I am still having trouble explaining why back feeding the dryer outlet is not the way to go so this is an up hill climb.

It is not surprising that more people get killed and injured after a storm than in it.

How about a suitably rated DPDT relay that is powered by the back up power source? PoCo power thru the NC contacts and back up power thru the NO contacts.

That was another idea that floated around the beer soaked brain storming session.

You still end up with how the relay in question was listed.

I found a likely suspect for the relay but I am not sure where to find the listing data for these approval numbers

UL E22575; CSA LR15734

There is a Russian site that pops on a google but I am not really interested in downloading anything from Russia.

Greg,

I, too, dealt with these questions two winters ago when there were widespread power outages & downed service entrances. I went out to do service inspections where the generator was hooked up to the new service & running. I advised these folks that our local POCO had the right to refuse service or disconnect the service, without notice, for improperly connected generators. This generally produced the desired result of them disconnecting the generator



The explanation to the wannabe electrician is that proper transfer equipment removes human error from the process. It seems that every hurricane season, I hear of at least one lineman killed by a generator that has been incorrectly connected (via the dryer outlet or other means) and someone forgetting to turn off the main breaker.

You might stress that intelligent people do idiotic things during an emergency, such as firing up the generator before inserting the plug in the receptacle. Also, the plug could be yanked out accidently or by a child.

Perhaps a proposal for the 2014 NEC should include mandatory jail time for anyone proposing this type of installation. :-')

I am still not sure what my neighbors are going to do. I think I have them thinking the right way. The snap switch/relay guy is still hanging on but at least he is not back feeding the dryer plug and trying to remember to turn off the main. The solution is elegant, if not totally legal. The only questionable thing is the listing of the relay he chooses. Since we shot down the snap switch idea, he is looking at a motor rated, 30a DPDT Potter Brumfield unit.

It turns out I will end up with a generator out of this whole mess when the dust settles. One of the guys is upgrading from a 5500w Briggs machine and he made me an offer I can't refuse. I am converting it to propane.

I am taking the easy way out with my transfer problem. My main panel is a natural for the main breaker interlock kit and I have always had a generator in the back of my mind so all of my critical circuits are grouped. I can turn off all but 6 breakers and have everything I need covered. I will still need to do some load management but I think I will survive.
My heavy hitters are still my well and house pumps.

Greg:
Jumping in here late into the conversation, have you given any thought to a manual transfer switch? Sq D used to make low amperage, double pole, double throw switches.

Just a thought

The main problem with a typical generator transfer panel is the amount of rewiring necessary to get all your loads over to the transfer panel. I really don't have the wall space for a 200a switch.
I also have the same problem as the neighbor in the 225 thread, I have loads in 2 buildings I want to serve.
Both of us have the pumps running off a panel in the garage.

For me, the main breaker interlock seems to be the easiest listed/legal solution. I really just have to swap a couple breakers around and add one for the generator input (with a retainer clip )

Greg:
Perhaps I was not clear. In lieu of a snap switch as discussed above, I mean the DPDT manual xfr switch.

Yes, a 200 amp is large for your situation and needs big space. The interlock plate solves a lot of problems for a lot of folks.

That idea came from my neighbor. I am still not sure what he is going to do.

BTW Dale Electric has a Siemens 60a transfer panel on sale for $44. I looked at it but I still can't figure out how I could wire it up in my situation. I would certainly be looking at that same situation of multiple circuits/feeders between buildings. It would even be harder for me than the neighbor. I would probably end up with 2 transfer panels and having to bury another feeder out to the garage. Suppose I could sneak a couple #10s in the current raceway with the house feeder from the generator but that would open another question. Would you have to derate?
It is a non-coincidental load.

When I was first learning the trade, the boss was most insistant that there be BOTH a mechanical and electrical interlock to prevent back-feeding - similar to what you see on a reversing motor starter.

So, we tied the breakers together for the 'mechanical' interlock. We also set up a pair of contactors so that the coil would energize (connecting generator power to the panel) only if both the generator was running and the house power was off. This was the 'electrical' interlock.

I Guess that all depends on whether you trust the service disconnect to actually disconnect all ungrounded conductors.

As far as I am concerned, If I trust it to protect me on the load side, I believe it will protect everyone on the line side.

I do believe it has to be a special circumstance that even allows back feeding the grid. My thought is when the average homeowner generator hits the locked rotor of a neighborhood full of air conditioner and refrigerator compressors the generator will kick out or burn up.
That is plenty of reason to insure you are transferring the load tho.