Circuit sizing?

[Paul Downes]

Need a little input from you electrical geeks,......... I mean brains. I just added two more high output fixtures to my wood shop. This was in addition to one I installed last year. I had 4 300 watt fixtures which were inadiquate for my tired eyes. I pulled these out of service and added 6 110 watt HO lamps. (3 fixtures) The ballast says the 110 watt lamp is rated @ 2.6 amps draw. Am I correct in calculating that I now have 15.6 amps total on the circuit? If this is true then I have exceeded the rating for the 15 amp breaker. I noticed that @ start-up it took a few miniuts for the 2 new fixtures to stop flikering. Sure hate to burn the barn/woodshop down. I was trying to avoid installing 2 new light switches. I believe it is code that light fixtures must be on a 15 amp breaker. While I did run 12-2 wire for the new fixtures the light switch runs and power source are of 14 gage wire.

[Rob Russell]

Let's keep this simple. Watts = volts * amps. If your service is 120 volts and you draw 1 amp, that's 120 watts. Your 110 watt light fixture is drawing a bit under 1 amp per bulb. If you have 6 bulbs, that would be about 6 amps and nothing to worry about.

There is no code that says lights have to be on 15 amp circuits.

It may be that there is a higher draw at startup/warmup and it's taking a while for the new fixtures to completely warm up, sort of like a street light heating up.

[Paul Downes]

Bob, the rating on the balast must referance to the start-up draw then. Maybe I should just pop a 20 amp breaker in for that circuit? I wonder if 14 gage wire is rated for 20 amps? The circuit run is about 60-70 ft. long.

[Chris Fite]

Usually, 14 gauge wire is rated for 15 amps.

[Rob Russell]

Bob, the rating on the balast must referance to the start-up draw then. Maybe I should just pop a 20 amp breaker in for that circuit? I wonder if 14 gage wire is rated for 20 amps? The circuit run is about 60-70 ft. long.

#14 is only rated for 15 amps when used in normal branch circuits.

[Paul Downes]

Rats, I suspected so. I always have some sort of vauge memory when working on electrical stuff. I'm a mechanical guy. I always teased my electrical engineer co-workers that they deal in abstract theories and I deal in concrete realities.:D I'm not an electrician, as is well evidenced by my blathering. I guess my choice is to upgrade the wiring to the existing switches, or put in new switches and wiring. I did pull out all the aluminum wiring that was in the barn. I always like to overkill things when I build something. I find the little added cost is a nice insurance policy.

[Rob Russell]

Why do you think you need to upgrade anything?