Generator Mod 1

[thomas52]

I've got an old Coleman 5K (6250 surge) backup generator with with two 120 outlets (double-blade & ground) and two 240 outlets (same but one blade turned 90 degrees.)
My electrician say I can't use it in my new house. I need 240 for my well pump, and 120 for the rest of the house.
He recommended a Generac 7K (12250 surge, electric start) with 2 120VAC 20 amp outlets, one NEMA L-5 30amp 120 VAC (3 blades in circle) and one NEMA L-14 30 amp 120/240VAC (4 blades in circle.) (see

http://feastinc.net/new_page_17.htm

- see halfway down near "rescue knife." - a nice generator, but a little tight on cash.)
Question: Can I use the old generator? If not, can I modify the old generator to accept a NEMA l-14 120/240VAC plug? Is there an 'adaptor' or 'converter' that I could use between the 'backup' breaker panel and the old generator? Please use simple terms, I'm way over my head here. Any help appreciated.

 

[OperaHouse]

I wouldn't be too fond of the 7K generator either. You can easily do this if you are disciplined. The generator is 110-N-110. The home improvement stores sell a switch panel that will switch the major devices (refrigerator, pump, furnace, central emergency lighting) from generator to grid. Depending on current, maybe only one device can be operated at a time. Better than nothing. This is not a concept that the other house members will understand or embrace.

 

[thomas52]

Thanks for your thoughts. For better or worse, I've already wired a separate panel in the house with a separate switch to disconnect from the grid and connect to backup power. In the past (at the old house) I was able to use the generator fine to handle specified outlets in certain rooms, etc. by switching over and plugging into the generator. I used an ammeter to determine the starting loads on the refrigerator, etc. to 'sequence' turning on each circuit. I could reconfigure the backup panel to exclude the well pump, and everything else would work fine; then I would have to figure out how to run the pump by itself, but it seems a 'backwards' solution.In a perfect world, I could fix the generator to accept the NEMA L-14 120/240 instead of JUST 120 or JUST 240 (separately,) but I haven't quite figured out how yet.

 

[thomas52]

See if this makes any sense?:
The four blades on the NEMA L-14 would be red, black, yellow & white, representing 240, 240, 120 & common/gound respectively. If I ran the wires through a box, or made an "adaptor," the red, black & white (common) could plug into the 240 outlet on the generator, and the yellow, white & bare/ground (?) to the 120 outlet.
I'm confusing myself. HELP! I KNOW it can be done, but can't quite figure how.

 

[RAMConsult]

Confusing yourself is one thing, killing yourself is quite another. Your problem lies with your combining the "common/ground" connection which are really two separate and distinct functions. In the US the four wires would be red, black, white and green. 240 volts between red and black, 120 volts from red or black to white. The white wire is the 'common' or neutral wire for deriving a return path for 120 volt loads. The green or bare wire is used exclusively as an equipment safety ground, no current should flow through it except during a fault.

The smaller generator has three leads: red, black and white, the frame is electrically isolated from the generator windings. You're supposed to attach a properly sized grounding wire from the lug on the frame to a solid ground in your home system, but this depends on your local regulations.

The larger generator automatically extends this safety grounding connection into your (properly wired)wiring system. The difference is subtle, but will determine if GFI's or CB's operate properly or at all.