Storage Batteries

[J Fimbianti]

article 480.6 is "overcurrent protection for "Prime movers"

what is the definition of a "Prime mover"

[Dennis Alwon]

I believe it is any equipment that converts energy from another source

[drcampbell]

In hybrid vehicles (including Diesel-electric locomotives), "prime mover" refers to the infernal-combustion engine, but the NEC doesn't apply to vehicles.

It sounds like 480.6 refers to batteries whose only purpose is starting infernal-combustion engines and are not tied into a building's electrical system.

[zbang]

Yep, "prime mover" refers to the engine/turbine turning an alternator/generator, or "the first thing that turns" in the system .

[raider1]

article 480.6 is "overcurrent protection for "Prime movers"

what is the definition of a "Prime mover"

480.6 permits batteries that provide power for starting, ignition, or control of a prime mover (Generator) to not have overcurrent protection for the conductors between the batteries and the starting equipment of the generator.

Chris

[ron]

Maybe I'm missing something but I don't see the words prime mover anywhere in 480.6.

[raider1]

Maybe I'm missing something but I don't see the words prime mover anywhere in 480.6.

Ron, I have pasted the 2017 NEC 480.6.

480.6 Overcurrent Protection for Prime Movers. Overcurrent
protection shall not be required for conductors from a battery
with a voltage of 60 volts dc or less if the battery provides power
for starting, ignition, or control of prime movers. Section 300.3
shall not apply to these conductors.

This was 480.5 in the 2014 NEC.

Chris

[ron]

Ron, I have pasted the 2017 NEC 480.6.

This was 480.5 in the 2014 NEC.

Thanks Chris, I have to get with the times.......

[publicgood]

Yep, "prime mover" refers to the engine/turbine turning an alternator/generator, or "the first thing that turns" in the system .

Agree.

NFPA 37: Standard for the Installation and Use of Stationary Combustion Engines and Gas Turbines

3.3.3  Engines. Prime movers such as internal combustion engines, external combustion engines, gas turbine engines, rotary engines, and free piston engines using either gaseous fuels or liquid fuels or combinations thereof.

[Sahib]

480.6 permits batteries that provide power for starting, ignition, or control of a prime mover (Generator) to not have overcurrent protection for the conductors between the batteries and the starting equipment of the generator.

Chris

It is a bit surprising that the code does not require it. In one incident I saw melting and smoking of 12V battery leads PVC insulation due to some short in the starter motor of a 30KVA generator.