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Mike772 04-22-2006 06:36 PM

Important about Generators
I have noticed an increase in homeowners wanting to install their own backup generators on their house. Or they want to buy a generator for some other use and use it during power outages.

This is important. Please understand the importance of a transfer or a bypass or disconnect switch.
Here's why. When there's an outage, the primary line is out (obviously). If a generator is hooked up to a house without the house disconnected from the power company's line, you will backfeed the transformer resulting in line voltage on the high side bushing. Transformers work either way, stepping voltage down or stepping voltage up. This line voltage will vary on different systems depending on what winding ratio of transformer you have. But from your generator you will be putting anywhere from 2400 Volts to 14,400 Volts on a line that the guys fixing it think is de-energized. And that my friends will kill. Even if that primary line is in direct contact with the system neutral or ground, the generator will feed that load without tripping the breaker on the genenrator.

Something to think about before just getting upset and plugging a generator in to the house out of frustration durring an outage.

Also call your power company and explain to them what you would like to do. They will be more than willing to help you understand and to make sure you have the right equipment. They also know that it's their employees lives at stake if it isn't correct, so they'll help.


didn'tdoit 04-23-2006 06:09 PM

can't you just turn off the main house breaker?

Speedy Petey 04-23-2006 06:56 PM


Originally Posted by didn'tdoit
can't you just turn off the main house breaker?

NO! This is NOT an option.
Doing it illegally and UNSAFELY is never an option.

didn'tdoit 04-24-2006 07:49 AM


Originally Posted by Speedy Petey
NO! This is NOT an option.
Doing it illegally and UNSAFELY is never an option.

unless your are an illegal immigriant.

Teetorbilt 04-24-2006 01:26 PM

I've been installing these at the rate of 2-3 a month. I pour the slab, mount the unit and often run the exterior conduit. From there a licensed electrician takes over. THIS IS NOT A DIY JOB!

frenchelectrican 04-24-2006 05:12 PM

myself i did see alot of generator installement some are pretty outright scarey with illegal connections i wish i take a photo of it some of you will drop the jaw when you see it

anyway,, i am master electrician and also i do install and repair alot of diffrent size of generators from little 3.5 kw gas/diesel unit all way to monster sized unit that can support the mid size city easly.

anyway i will like to advise to the D I Y's please do heed the warning for connection for the generator hook up and make sure you have either manual or automatic transfer switch at main panel [ some state or local code dont allow use the subfeed box for this at all ].

have a electricican to hook up the connection this is the safest way for us and the owner of that place too .

thanks again

Merci , Marc

playintennis5274 04-29-2006 01:13 AM

important about generators..
geee ... maybe that's one of the reasons the power company has those large fuses that can open from a handle disconecting that section from any possible power from anywhere..

Speedy Petey 04-29-2006 06:52 AM

Geee, if I read you correctly you are being facetious.
That is not their purpose, to portect your sorry a** from killing a line worker. Power can feed in any direction and if there is power on both sides of the switch it will make as nice BOOM when closed.
Also who knows when or where a careless homeowner will connect one of their "easy" generastor hookups. The linemen could be just connecting wires of fuses when a backfeed comes along.
It CAN and HAS happened!

Good luck with your theory. 'Cause it don't hold water! :mad:

Mike772 04-29-2006 04:50 PM

No playintennis5274, that's not it.
Not to single you out, but do you know anything about electricity?
My rubber gloves protect me, not fuses. But you didn't know that if by chance the outage is caused by trees downing lines, lots of rural folks have chainsaws and are willing to get roads open when blocked by trees. If you don't know there is power lines under or in the trees, you wouldn't see them until it is way too late. Trust me when those lines are not easy to spot.
Like I said, a generator will feed a direct fault without tripping the breaker on the generator. Now I'm talking about when backfeeding a transformer and faulting out the high side.
Go to a hotline demonstration put on by your local power company, that way you can maybe understand.

To others, Speedy, thanks for taking this matter serious.

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