Latest Discussions : Electrical & Lighting

safetybob04

12:09PM | 02/29/04
Member Since: 02/28/04
2 lifetime posts
I have a question related to branch circuits.

How many 300 watt incandescent lamps can I install on a 20 ampere, 120 volt branch circuit?

Thanks for your help.

bcelect

01:04PM | 02/29/04
Member Since: 02/21/04
138 lifetime posts
Seven

bcelect

03:03AM | 03/01/04
Member Since: 02/21/04
138 lifetime posts
the answer is six. not seven.


Tom O

01:21PM | 03/01/04
Member Since: 09/17/02
476 lifetime posts
You could really start a serious arguement with this question.

Assuming that the calculation is done at 120 volts and that the lamps are rated at 120 volts, then the answer is 6 for circuits installed in buildings other than a dwelling.

For a general purpose lighting circuit in a dwelling, 8.

Tom

bcelect

02:12PM | 03/01/04
Member Since: 02/21/04
138 lifetime posts
Lets say the lights will be on for more than 3 hours and you may not load the breaker more than 80% for a continuous load.


Tom O

02:41PM | 03/01/04
Member Since: 09/17/02
476 lifetime posts
I realize that any load could be a continuous load, but lighting loads in a dwelling are not considered as such. Therefore, on a 20 amp circuit, you can have a 20 amp load.

On the other hand, in an office or store, the lights are considered to be a continuous load, hence, fewer 300 watt lamps on the same sized circuit.

Tom


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