Thanks for the input. I have an electrician coming out to inspect the
whole set up, but if you experience a brown out about 7:00 pm (MST) on
Friday after Thanksgiving you know what happened.
Gus
John Grabowski wrote:
wrote in message
...
On 19 Nov 2006 16:42:17 -0800, "gus" wrote:

We are putting light bulbs on a large outside tree in a city park. We
have six 100 foot strings of 100 C-9 lights. We have two 20 amp GFI
circuits available. I plan to put 300 lights on each circuit. My math
shows 2300 watts available and C-9 bulbs use 7 watts. This comes to
2100 watts. I will use 12 guage extension cords. The light strings
and bulbs are commercial grade. This all looks good on paper, but I am
worried because there is not much room for real world error. Does
anybody have experience with this many lights? Wasn't there a movie
about a guy causing a large scale blackout when he threw the switch on
his house decorations? I don't want to be that guy. Any help you can
give me would be appreciated.
Thanks,
Gus

The normal rule is you don't put a load greater than 80% of circuit
capacirty itf it will be on longer than 3 hours.
Christmas is usually when the NEC goes on vacation though. If you
spread these out across 6 cords, plugged into the receptacles directly
I don't really see a huge problem thouigh since, technically it is a
700w load and a 1400w load on each, not a 2100w load. The circuit
itself should take it.


Fortunately circuit breakers do not take holidays off. They are only rated
for a maximum of 80% continuous load of 3 hours or more. Depending on the
age, quality, and condition of the circuit breakers you may not get them to
stay on for that long. That's about 16 amps for a 20 amp circuit.