NEC User
Senior Member
- Location
- Marlboro, NJ, USA
My understanding is:
NEC recommends having a maximum of 3% voltage drop from the last circuit breaker to the last load to provide a reasonable efficiency of operation.
NEC recommends having a maximum of 5% voltage drop from the feeder to the last load to provide a reasonable efficiency of operation.
My loads are all lighting and I'm restricted to using conduit within a concrete parapet which is filled with existing wiring. Due to the other circuits I can't increase the wire size. My intention is to reuse the existing wiring.
My wiring diagram consists of an existing 120/208V service from the utility to an existing loac center which is a 120/240V panel which uses single phase breakers to feed all 120V lighting loads. The utility service is located within 5 feet of the 120/240V panel and the voltage drop is less than 1%.
My voltage drop calculations from the panel to the last light come to 4% for two of the breakers.
My Questions are:
Are my ok even though I get a 4% voltage drop on the branch circuit since the total voltage drop is less than 5%?
What is what is a reasonable efficiency of operation; will the equipment still work just cost more money in utility bills? What happens if these recommendations are exceeded? Is there's some room for error where the equipment will still work?
NEC recommends having a maximum of 3% voltage drop from the last circuit breaker to the last load to provide a reasonable efficiency of operation.
NEC recommends having a maximum of 5% voltage drop from the feeder to the last load to provide a reasonable efficiency of operation.
My loads are all lighting and I'm restricted to using conduit within a concrete parapet which is filled with existing wiring. Due to the other circuits I can't increase the wire size. My intention is to reuse the existing wiring.
My wiring diagram consists of an existing 120/208V service from the utility to an existing loac center which is a 120/240V panel which uses single phase breakers to feed all 120V lighting loads. The utility service is located within 5 feet of the 120/240V panel and the voltage drop is less than 1%.
My voltage drop calculations from the panel to the last light come to 4% for two of the breakers.
My Questions are:
Are my ok even though I get a 4% voltage drop on the branch circuit since the total voltage drop is less than 5%?
What is what is a reasonable efficiency of operation; will the equipment still work just cost more money in utility bills? What happens if these recommendations are exceeded? Is there's some room for error where the equipment will still work?