I would like to install an interlock in my electrical panel to allow for the use of a generator. I do not own a generator and may never own one, but I thought it better it set things up for little cash now than to retro later.
SO …. do people buy 120 volt or 240 volt generators if they are looking for 6 to 9 kw? This is relatively important to know and plan for now as I beleive it means teh difference between having a 50 amp bipole or singel pole backfeed breaker in teh box (correct term???). And also it may or may not make a difference on teh type of plug in to wire up to plug the generator into, (might be teh same plug of 240 or 120) ??????????
Information????? Thanks.
did I say my supplier was in France?
Replies
Typically anything besides a small camping style generator is 120/240. You can usually find an interlock kit for most new panels.
The backfeed breaker needs to be next to the main breaker in the first pair of slots.
Up to ~6kw, you will use a 30a breaker and an L-14-30 plug.
Larger than that will usually end up with a pin and sleeve plug and a 50a breaker or more..
Couple more questions
Thank you so much Greg.
You say most non-camp style generators are 120/240 Volt. What does that mean? Does that mean that they are capable of being used to directly plug 120 volt .. say tools .. into the unit AND Or able to produce 240 volts in other applications? Is there typically a switch to determine which voltage? Or is it as simple as if you use the generator to backfeed a bi-pole breaker you drive 120 to each of the two panel phase bars? Please explain if possible.
I guess the other thing I need to figure out is if I need to go bigger than 6kw if and when I would chose to purchase the generator. Just not that sure how much I need a generator. Service has been very very good in teh area with only short outages. But installing the interlock before the panel is loaded with breakers in teh wrong place, before teh walls are sheetrocked and cover teh route for the wire to the plug, etc is easier now and relatively cheap.
Thanks again
Yes, a 120/240 rated generator will have both voltages available. Just remember to balance the 120v loads across the plugs.
They usually indicate which receptacles are on each phase.
If you use the 240v receptacle, you can feed right to the interlocked, back feed breaker or transfer switch. (Red, Black, White and a green ground)
The 5.5-6kw seems to be a popular size for portable generators for occasional use. Usually larger ones are hard wired into transfer equipment and you are getting into the "auto start/switchover" neighborhood.
Looks like I am on the right track
One last question.
IF AMPs times VOLTs equals watts, then how can a 30 amp breaker be appropriate for a 6kw generator?
30 amps X 120 Volts = 3600 watts vs teh 6000 generator OR!!!!
is the issue a bipole 30 amp breaker which makes the equation 30 amps X 240 Volts = 7200 watts.
???? thanks again
They are rated at 240 volts so your second calculation is the one.