Generator Wiring Question.

[techman]

First of all, as stated, a transfer switch is to prevent any possibility that the generator and utility power are never interconnected. If a utility worker is on a pole near your house to fix an outage, and you accidently backfeed the power line, the pole transformer and wiring could become hot and kill the guy. A transfer switch is required by code.

As for transfer switches, the full load switch is quite expensive as you learned. The one you saw (with your link) will transfer a limited number of circuits and is lower cost. This allows the critical circuits to be powered up. Installing one is not beyond the capabilities of a DIY'er who has installed new circuits and breakers in a panel.

The other thing to look in to is a main panel by Square D. They make a normal panel that has the provision to have a breaker that can be connected to the generator to backfeed the entire panel, as you mentioned. The difference is that there is a mechanical interlock lever that does not allow the main to be on when the generator breaker is on and visa versa. It may require replacing your breaker panel to use this one, but that may be a not too unreasonable price in the end.

paul

 

[Justaplain]

I have 3 double pole/double throw wall switches in series with the panel and load.. One pole to gen set and one pole to the service. One is wired to a 240 pump and the other two to freezer etc. They cost me less than 10 bucks per. bcs

 

[George2615]

I have a manually switched set up for my generator. My generator is a Hobart 250 NT welder/generator rated for 10KW and has a 50A 220V receptacle on the front. I have two electrical panels so I installed a separate main knife switch disconnect in my garage that feeds a panel in the garage and the one in the house. In the garage panel I installed a double pole 50A breaker and fed out a flexible 4 wire lead cord (2 hot,1 neutral,1 ground) and put a 50A male plug on the end. I also mounted a dummy 50A receptacle in the wall by the panel to plug the whip into when not in use. When I lose power, I roll the generator outside the garage door and fire it up. While its warming up I verify the main disconnect from the street power and my 50A breaker are both turned off. Then I unplug the whip from the dummy plug and insert into the generator. At that point I turn on the 50A breaker which then feeds power back into the house. All I do then is watch the neighbors house for signs of street power being restored then reverse my steps to go back to normal power. I typed up a step by step procedure check list to follow and it is posted next to the panel so if I wasn't home anyone could follow the procedure to have house power.
Anyone with a basic knowledge of electricity should be able do this. If you are unsure then hire someone who is knowledgeable. Just be sure the breaker and lead cord you install are rated for the amperage of your generator. I see no need to pull the meter if you have a main disconnect switch. Your 30A generator may not run all items in you house so you may have to be selective and turn off some additional breakers. My previous generator was 5KW w/ 6250 surge and had a 30A plug on it as well. It did a fair job but I shut off many non essential breakers while using it. As some others have said, there is a fully automatic system that will not allow generator power to backfeed into street power. If you have an auto start generator you need an automatic transfer switch. If you have a manual start generator you are responsible for ensuring that your power does not backfeed street power. There is always a chance for human error that could injure or kill someone.

 

[1962]

i pull the meter too. been doing it since the early 90's. i cut the seal wire with wire snips. and replace it when power is back on-grid. the power co wont really take notice unless they start seeing a huge loss per month in your electric consumption. like if i was stealing electricity. i also disconnect the main at the panal. the panal is well grounded, and the generator is earth grounded at it's outside location. the meter socket is about 5' off the ground and i pop a plastic guard over it for safety, and for freezing rain if its winter.
#1 pull the meter and cap it
#2 fire up the genny and let it warm up
#3 select the circuits i want to power at the panal
#4 plug in the genny to house disconnect(main line)
#5 throw the genny power to house switch

 

[VA_Joe]

techman makes good sense.

Use a mechanical interlock to ensure that the mains and gen power are never connected. Not using one could result in both death to a lineman and a manslaughter charge to the person that didn't follow established code (it is no different than killing someone while driving drunk). It's not worth ruining two families over a $50 switch.

BTW - I use the 60 amp Square D mechanical interlock along with a second subpanel for all the generator circuits. The advantage of the 60 amp box (over the 30 amp) is that it gives you more control over which circuits to run at any given time on generator (i.e. even if you have a 30 amp genset) but still supplies more than enough capacity for running all circuits off the mains.

Joe

 

[nobull1]

BTW - I use the 60 amp Square D mechanical interlock along with a second subpanel for all the generator circuits. The advantage of the 60 amp box (over the 30 amp) is that it gives you more control over which circuits to run at any given time on generator (i.e. even if you have a 30 amp genset) but still supplies more than enough capacity for running all circuits off the mains.



I agree, when I had mine installed that was a question the electrician asked. At the time I didn't realize that a 60 amp would give me access to a lot more circuits that I could potentially use. One thing though in our area is if you go to a 60 amp you have to have a manual disconnect switch installed in line. Why I don't really know but that is code.

 

[Shimon]

Hmm...that's interesting about the electric companies not caring too much about pulling the meters. I'll have to call PSE to see what their policy is. Learn something new every day (especially on TBN).

 

[QRTRHRS]

The automatic stand alone systems need to have the feed from the meter to the box changed. It has to run through the transfer switch then to the box. The meter must be pulled and the hot leads to the terminals must be respected. Those systems are slick, the genset can be set up to run periodically. The only drawback is most electricians are not all that well vesed in the genset engine maintanence.

I have not seen one but I think Square D has some kind of breaker that you can wire into to reverse feed. The breaker isolates the box somehow? But then you would need a Square D box.

One of the safest ways for someone who capable of working inside the box but does not want to pull the meter,etc. is to go with a manual transfer switch. With a manual switch, depending on the size, you choose your most important circuits. Each switch has two wires. You remove the hot from the breaker, wire nut that to one wire then secure the other to the breaker. The switches have three positions, line, off or gen. Normally on line, when the power goes off, you fire the generator up, then throw each switch to gen.

The wire from this type of switch takes up a lot of room in the box. If your box is already stuffed, it may be time to upgrade anyway. And, although simple, explaining the procedure to my wife is like teaching her to program the VCR.

Your local codes may have a say in what you do when you set up a backup system.

 

[Jagmandave]

Why not use a simple either/or switch rated for your main panel?

When you're running on line, it's in that position, when you pull it into the gen position, you're disconnected from the line. Then all you have to do is make sure you're not overloading your genset on startup, by throwing your heavy load breakers off. Seems simple enough to me......

It also acts as a service disconnect in the middle "Off" position

 

[QRTRHRS]

Would that not involve pulling the main and rerouting the feed for the installation?

The beauty of the manual transfer switching is that you initialize one circuit at a time. That and someone with an average knowledge of electricity to do the install.

By the way, not that it is any big deal for the average home owner but the self starting gensets with automatic transfer are hardly transparent. There will be a momentary "glitch" until the genset takes over.