How many lights on a circuit?

[nwav8tor]

I read elsewhere that a lighting circuit should be limited to not exceed 80% of the "calculated wattage capacity" of the circuit. Their example showed 120v x 15a = 1800 wattage capacity. So using an 80% limit, they said the circuit should be limited to 1440w max. I take it that this is for standard incandesent lights and not flouresent light circuits. Is that correct?

For flouresent fixture circuits, should you just add the amperage rating of the ballasts in the fixtures and limit that to 80% of the circuit breaker ratiing? For example, if the ballasts are rated at 1A per 2-tube 4' fixture, can I put up to 16 fixtures on a 20A circuit or 12 fixtures on a 15A circuit?

Thanks,
Paul

 

[pattenp]

For fluorescent using the ballast amperage is the best way to figure it. Your example is good.

 

[Toomanytools?]

Think you might get a surge when you turn on the lights, so 16 on a 20a is 80%. That 20% should take care of any surge about 4amps. But I have no freakin idea should be ok?

 

[nwav8tor]

For fluorescent using the ballast amperage is the best way to figure it. Your example is good.

Thanks pattenp

 

[nwav8tor]

Think you might get a surge when you turn on the lights, so 16 on a 20a is 80%. That 20% should take care of any surge about 4amps. But I have no freakin idea should be ok?

Not too worried about any "surge." I plan to split the 15-18 lighting fixtures into two 15A circuits with no more than 6-7 fixtures on a switch leg.

Paul

 

[SuperSocket]

I would use the max rating of the fixture, not the bulb type you plan to use. You could literally get away with running dozens of fixtures on one circuit by simply swapping bulbs to LED's, but if someone behind you comes and puts in incandescent it will be a big problem.