[Bell925]

I have a hrose ranch and installed five 500 wattt exterior halogen lights to the barn entry and wash rack areas on an existing 20 amp circuit. After the lights have been on for a few minutes the circuit breaker trips. Obviously, I've over loaded the circuit. My Questions are :

Can I change out the 20 amp breaker to a 35 or 40 amp breaker?
Or do I have to run a new wire to the panel and split the lights? I am trying to avoid as it involves a long run about 20 feet up in the barn rafters back to the panel.
The panel is cablable of holding the additional load.

Thank you for your help!

Dennis

[donf]

Lets start with the easy stuff first.

Are you using 20 amp @120 or 240 VAC?

How many lights per circuit? Did you calculate the load at 1.25% because the lights will be on for more than 3 hours continuously?

The answer to your original question is no. You cannot increase the breaker size without changing the conductors size.

20 amp requires at least 12 AWG copper. 30 Amp, requires 10 AWG copper and 40 Amp requires 8 AWG copper.

If you are using aluminum, then you need to increase the size of the wiring.

Also, the type of insulation will gate the amperage that the conductor can sustain.

[Bell925]

Don... thank you for info, I was afraid that was the case. I appreciate the load calculation, so I can wire this correctly.

[Bell925]

Don... thank you for info, I was afraid that was the case. I appreciate the load calculation, so I can wire this correctly.

[edtech87]

What is the wire size you have? Should be at least 12AWG copper as donf stated.
The 20A circuit breaker is just big enough for the (5) 500Watt lamps - could you downsize one or two to 300Watt lamps to just get by without re-wireing.

If you really want to avoid stringing another wire and are willing to live with shorter bulb life and adding another light, you could switch to 240Volts by changing to a 2 pole breaker and put 3 groups in parallel of 2 lights each, in series and that will cut down the amps to half of what you have now. Most wire is rated to 600Volts and should be able to take it. Lamps have to match in the pairs exactly, so when you factor in the manufacturing differences, they do not and will find some lamps fail prematurly because they see more voltage than their partners. If the wire is old, I would not try this.

[stanfortyman]

Edtech, please notice that the thread you are replying to is two years old.

[tkrussell]

Not only is Ed answering questions 2 years old, he is incorrect.

Since when can a 20 amp 120 volt circuit handle 2500 watts, 5 lamps at 500 watts each?

Last I looked, Ohm's Law states:

P=EI
20 x 120 = 2400

A 20 Amp 120 Volt circuit can only handle 2400 watts, not 2500 watts, and that is if the circuit is to be considered as non-continuous, or operate no more than three hours, clearly not exterior lighting.

Instead of suggesting using a 240 volt circuit and connecting lights in series, why not suggest using 240 volt lamps?

Ed. Please note the date of threads before you answer, and refrain from answering questions older than a few months.

And please answer accurately.

This thread is closed.