Connecting a backup generator.

[jmetrisin]

Hello,

I have a 5500 watt generator that I bought for power outages that I want to connect to my home. I would like to do this as follows. First, I turn off the main breaker to prevent back feeding. Then turn off all non-essential breakers leaving only what I want to run (a few lights, well pump, etc.). I would like to connect the generator to a 220V 50A (3-prong) plug that's available in my garage. The generator has a 220V 30A (4-prong) outlet.

My question is how to build the connection wire with a 3-prong plug at one end and 4-prong at the other, and if this is safe to do? Also, will the voltage be stepped down correctly through my home wiring to the 120V circuits?

Thank you.

Joe Metrisin

[Ron]

It is not safe to do and is a code violation.

[dualvet]

As Ron said it is a violation and unsafe practice to do as you
want.

You will need a "Transfer Switch" between your Gen set and the
"main" electrical panel.

I would advise getting a licensed electrician to do the job.

gl

Ed

[jmetrisin]

Ed, Ron,

Thanks for your quick responses. I'll probably go with the transfer switch per your suggestions, but I'm curious why connecting the generator to my home is unsafe? After hurricane Frances, I had several people in my neighborhood run their generators by connecting them to their 200V 30A dryer plugs, and ran this way for a week with no problems.

If this is dangerous, I'd like to be able to explain to them why, since it seems to work.

Regards,

Joe Metrisin

[Ron]

The function of just connecting the generator is not unsafe if certain procedures are followed. The code mandates that some of those procedures be mechanically interlocked so you can't forget and hurt yourself or a utility worker. Hence the transfer switch.
In addition, your connection to the house through the transfer switch needs four conductors, as the neutral to ground connection within the generator must be disconnected unless you not only switch the two hot conductors but the neutral too.

[Speedy Petey]

Originally Posted by jmetrisin

Ed, Ron,

If this is dangerous, I'd like to be able to explain to them why, since it seems to work.

Joe Metrisin

Classic case of "It works, so what's the problem". "Everyone else is dong it, what's the problem". Everyone else is not that bright and has no concern for safety!

You have a male to male extension cord which in itself is inherently VERY dangerous and very much against code.
You are backfeeding your service without the proper overload protection which can overload your generator and wiring.
You have the distinct possibility of killing a line worker if several procedures are not followed by anyone who has access to your generator.

I personally feel that a HUGE label should be placed on each and every generator sold reminding that the owner bears any and all responsibility to hook up the generator properly. The fact that you may go to jail should also be mentioned. Killing a line worker may not hold much water to some people but the though of going to jail might!

[Roger]

Jmetrisin, this is a very unsafe application but there are many many people across the country doing this with their portable generators. The fact that several people in your Florida neighborhood are doing this makes it doubly unsafe. An accidental backfeed to the utility by someone "forgetting" to turn their main breaker off will go through the utility transformer jumping that generator voltage to something in the area of 7200 volts. You have hundreds of linemen in Florida right now trying to restore power , that is all they need is the worry of being electrocuted while they work on power lines. The use of a transfer switch prevents the possibility of a utility backfeed. Also most utilities have requirements and an onsite inspection needed for approval of standby generator systems. This of course would be difficult right now in your area. Remember to that just turning the main breaker off only disconnects the two hot wires but does not disconnect the neutral. With the structural damage to the homes in your area it is possible a wiring fault as a result of this could place 120 volts on the neutral which would then backfeed to the utility. Anyway there are very inexpensive types of transfer switches available. Use one and give those linemen a break....Roger

In the green and yellow links at the top of this page you will see a yellow block labeled generators click on it and you will be able to read about the unsafe and then examples of safe installations and use of generators authored by one of our site creators and administrators Warren Goodrich.

[jmetrisin]

After doing a little research, I can see why so many people don't bother with the transfer switch. They typically cost $200-$400, and installation is another $200 or so. The total cost is as much as the generator!

The switches I've found on-line seem more complicated than they need to be. They all provide individual switching to 6 or more circuits in your main panel. Why can't I find a simple switch that toggles the whole house between line power and generator? I could then use the main breaker panel to switch on the circuits I need.

Regards,

Joe Metrisin

[Roger]

There are transfer switches at Home Depot for around 100 dollars...Roger

[Speedy Petey]

Originally Posted by jmetrisin

After doing a little research, I can see why so many people don't bother with the transfer switch. They typically cost $200-$400, and installation is another $200 or so. The total cost is as much as the generator!

So cost is more of a concern than safety? I see. I think I'll cancel my auto liability insurance. It's too expensive and too much of a bother. If I kill someone with my car (whether I ment to or not) I'll deal with it later.

Originally Posted by jmetrisin

Why can't I find a simple switch that toggles the whole house between line power and generator?

You can. The "simple" switch is usually a few hundred dollars and switches your whole service over manually. It is a double throw switch so the utility can never be backfed. I strongly advice against using a whole house transfer switch with a $500 generator though.