Fire pump generator conductor connected without overcurrent protection

[hhsting]

Those 100 amp breakers are not connected to the fire pump.

No but the conductor that feeds fire pump is connected to line side of 100A internal breaker. So the fire pump conductor from gen set to 200A enclosed breaker has no OCPD

 

[infinity]

No but the conductor that feeds fire pump is connected to line side of 100A internal breaker. So the fire pump conductor from gen set to 200A enclosed breaker has no OCPD

Correct so why mention the 100 amp CB as it is not in the fire pump circuit.

 

[hhsting]

Correct so why mention the 100 amp CB as it is not in the fire pump circuit.

Well what i was trying to say was fire pump conductors from gen set to 200A enclosed breakers have no OCPD. Still you all say they are feeders. I dont see these as feeders. So how are they feeders?

 

[infinity]

Still you all say they are feeders. I dont see these as feeders. So how are they feeders?

I never said it was a feeder. See post #5.

 

[hhsting]

I never said it was a feeder. See post #5.

There is no unlimited tap rule for generator in NEC 2017. I see for feeders and transformer. Where is it for generator?

 

[augie47]

Service conductors to a fire pump are often fed underground from the POCO transformer to the FP controller service disconnect without added OCP.
Why would a generator feed not be similiar

 

[infinity]

There is no unlimited tap rule for generator in NEC 2017. I see for feeders and transformer. Where is it for generator?

What would you call the conductors that are coming out of the generator? They're not a branch circuit, not service conductors, so what's left?

 

[hhsting]

What would you call the conductors that are coming out of the generator? They're not a branch circuit, not service conductors, so what's left?

By similar analogy transformer secondary conductors are not service, not branch circuits so that makes them feeders? You don’t use feeder tap rules for them. Code has special section separate from feeder taps.

Why would generators conductor no ocpd be feeders?

 

[PD1972]

If your jurisdiction has adopted NEC 2017 and onwards, look at 445.13(B) which sends you to 240.21(B) - Feeder Taps. This allows you to provide tap conductors from the terminal box of the generator without main-line OCPD.

The listed overcurrent protective device or combination CT/overcurrent relay referenced in 445.13(B) is not the main-line OCPDs you would find on a consultant's drawings. It's the protection designed/selected by the generator manufacturer to protect the generator and not the conductors connected to the generator.

 

[hillbilly1]

Generators do not have to meet the locked rotor requirement, they just have to be able to start and run the fire pump. A lot of engineers will load shed the optional loads in order to have a smaller generator.

 

[don_resqcapt19]

By similar analogy transformer secondary conductors are not service, not branch circuits so that makes them feeders? You don’t use feeder tap rules for them. Code has special section separate from feeder taps.

Why would generators conductor no ocpd be feeders?

But they are a special case of feeders and have their own rules because they are a special case.

 

[tbassler_99]

I have only done a few fire pumps. The theory is that you want the fire pump to burn up before the building. Pretty much the opposite of the rest of the NEC.

I thought you sized the OCP at the locked rotor current amount of the pump plus any other pressure pumps and controls on the circuit to run indefinitely. The code section that applies here is 695.

 

[renat_electrician]

Hello,

I have a question, what if a fire pump 10HP, 240V single phase, FLA 50A, LRC 300A, what would be service size from Hydro, 400A? Imagine no any other loads just, hydro service for fire pump?