Found a 5500 watt generator on craigslist that I may buy, but am a little confused on the calculations. What I mean is if its 5500 watts would that mean I can power 45 amps of 120 volt items or 22.9 amps of 240 volt items? (5500 / 120 or 240) I dont understand how this can be correct when it has a 240 volt 20 amp twist lock that would be tied in. You wouldnt run number 6 wire to a 20 amp plug based on the 240 volt calculation would you?
Generator Calculations?
- Thread starter craig1980
- Start date
theoldwizard1
Well-known member
The real question is, what is the breaker size ?
If the 240V outlet has a 20A breaker then you can still pull more power through the 120V outlets which have separate breakers.
If the 240V outlet has a 20A breaker then you can still pull more power through the 120V outlets which have separate breakers.
Rob_b
Well-known member
Craig, it would be good to know the model you have but in all likelyhood, the 5500watt output would be surge watts and maybe 4500-5000 constant output. Yes, you could run up to 45.83amps (5500w /120V = 45.83amps) but I'd bet your going to be pushing it. The 240V side just halves the amps but you don't need to use a #6 wire. A #10 is all you'd need here while trying to use the 240V side full load.
Thanks Rob! this is what I am looking at. http://www.sears.com/briggs-stratto...1x000001&kpid=07133139000&kispla=07133139000P
Looks like the surge is 6250
Looks like the surge is 6250
frankzlt1
Well-known member
What are you going to use it for? Are you going to put a gentran manual transfer switch in to run different circuits in your house? The generator has a 30 L14 plug on it so you can plug a cord from the generator to a transfer switch.
It will be used for emergency power for a house. I am hoping to power a few lights throughout, propane furnace, refrigerator, and the well pump. It will probally be hooked u to a 30 amp outdoor outlet then feed a 30 amp breaker in the main panel with a interlock.
theoldwizard1
Well-known member
Most of your loads a 120V, except probably the well pump. You will have plenty of power as long as your 120V loads are evenly distributed between both legs.
IMHO, using an interlock is the most cost effective way of hooking a generator up to a house.
ishiboo
Well-known member
It has a L14-30R which is a 30A, 240v receptacle. There is not 45 amps available on a single 120v... it's two 120v legs, so that 45A is divided between the two. 22A per leg on a 30A outlet.
The 5500 will run what you want just fine. Use a 30A outdoor inlet.
Use a 30A outdoor inlet. [/QUOTE]
How is this wired? Generator is wired to the outdoor inlet I understand. Then to a 30 amp 220v breaker I understand. Then what, switch off main breaker in the panel and switch on the 30 amp breaker that is fed by the generator?
[/QUOTE]How is this wired? Generator is wired to the outdoor inlet I understand. Then to a 30 amp 220v breaker I understand. Then what, switch off main breaker in the panel and switch on the 30 amp breaker that is fed by the generator?
ishiboo
Well-known member
Use a 30A outdoor inlet.
How is this wired? Generator is wired to the outdoor inlet I understand. Then to a 30 amp 220v breaker I understand. Then what, switch off main breaker in the panel and switch on the 30 amp breaker that is fed by the generator?
[/QUOTE]If you are using a panel interlock, yes. It needs to be mechanically configured so you must physically switch off the main breaker before switching on the generator feed.
^ Note the piece of sheet metal, two nuts, a sticker and another $.50 piece of metal to hold down the 30A breaker. Square D sells that for about $56 retail
An external transfer switch provides this interlock by being a double-pole/double-throw switch.