Question about generator interties

[David Nebenzahl]

I *think* that's the correct term, but I'm not sure; it's the gizmo one would put between a small generator, your house and the utility connection, to cut in the generator and take you "off the grid" in case of a power outage.

Yes, I tried a Google search but didn't find anything useful. Have a customer who's asking about this. In fact, they mentioned the dreaded male-to-male plug that was ridiculed here not long ago. Thankfully I've talked them out of using *that*. (At least they knew that you've gotta disconnect from the utility lines if you connect a genset to your house.)

I'd like something basic, not too fancy, but smart enough to handle the whole connect/disconnect routine safely in case of an emergency. Say in the 5-10 KW range.

[James]

It is called a Transfer Switch. It can be bought at Lowe's or Home Depot.

Should be installed by a qualified electrician.

James

[Erma1ina]

I suspect that "the gizmo one would put between a small generator, your house and the utility connection, to cut in the generator and take you "off the grid" in case of a power outage" is a "TRANSFER SWITCH" (a manual one likely would be fine and relatively inexpensive - my 1-circuit, 15 amp was less than $100) NOT a "grid intertie". An intertie (relatively expensive) would allow him safely to feed power back into the grid. Here's a link for some info:

[ransley]

Transfer Switch. Look for prewired complete kits. Generac has a kit prewired anybody that has no fear of working in a panel can install, it has labeled wires its prewired, 6 -15a circuits-2 watt meters to balance the gen. It can power one 240v circuit and 4- 120v or 6 120v. It comes with exterior cable to gen, exterior weather box and outlet, several big plugs for different gens. I got it free at lowes with a

5500w generac. Its about 2-300 retail. There are other makes, just get a complete kit its alot cheaper. If the kit was bought by part singly, it might be 400+. Lowes has at times had specials where its free with a gen.

[RBM]

There are a few ways to safely do this. First method is standard double pole double throw transfer switch and generator panel. This method is the most costly and requires a sub panel dedicated to circuits you want controlled by generator power. A feeder from the main panel and a feeder from the generator are brought into this switch, and an output line from the switch feeds the sub panel. All the loads must be relocated from the main panel to the sub panel.

The second method is a prewired generator transfer panel. These come with a number of circuit breakers and single pole double throw switches prewired and you attach this next to your main panel and reconnect whatever loads you'd like controlled by the generator, to wiring in the panel. They also have a male twist lok plug built into the face of the panel for easy connection to the generator.

The third method is a main panel lockout. This is a retrofit device made specifically for certain make and model panels that allows you to backfeed generator power into the main panel and mechanically prevents the main service disconnect from being energized at the same time as the backfeed breaker from the generator

[Jim Elbrecht]

-snip-

Here's one for

[RBM]

I'd be a little careful with this. The picture shown does not match the description.

[ransley]

The Generac I have has no plug on the panel, it came with a weather proof exterior box and socket. If you have to plug it in on the panel it means and extra long and very expensive by foot price, exterior grade 4 wire 8-10ga cable, and you will need an opening to feed it in the house. The hardwire exterior box was the biggest job, but it makes hooking it up quicker and was cheaper than if I had used cable to the basement. For an exterior box and socket you will spend near 100$ +, that is included in the generac kit I have. The box there looks good, but also the extra sockets in the generac kit are worth 60-80$, Id say shop for the complete wired kit so you buy nothing extra at big cost.

[ransley]

Check Lowes, to see if they have the free give away panel, with a gen deal. The Generac kit panel has worked well for me and was easy to install.

[Frank]

I left mine to an electrical contractor who also replaced my original panel. I know you can DYI but I have never done major electrical work and decided to let a pro do it.

[Pete C.]

The third method is by far the easiest and most flexible if an interlock kit is available for your main panel. I use the Square D kit for my QO panel and it works well. The nice part is that since you are back feeding through a dedicated circuit breaker this setup can handle up to a 30kW generator (125A max branch breaker size), just as easily as a smaller generator. It's also the most cost effective since the kit is ~$30 + whatever size generator breaker you need. Installation also takes very little time and effort.

If you don't have a main panel that an interlock kit is available for, method number two is generally best for the generator size range indicated. The full transfer switches (method one) are generally not economical choices for small generators.

[David Nebenzahl]

On 1/10/2009 12:38 AM Erma1ina spake thus:

Thanks. Amazing how much better a search goes when you use the right term!

[Van Chocstraw]

Just turn off the main breaker and you're off the grid.