Twist

[hhsting]

NEC 2017 Section 695.6(C) and section 430.31 both says overload protection for Fire Pump is prohibited.

I have backup generator feeding Fire Pump that has internal overload protection in generator by manufacturer of the generator.

I do see the exception 2 in NEC 2017 section 695.6(C) to overload protection regarding standby generator since I have 124A fire pump load and generator is full load is 601A but that exception is very hard to understand what it means.

Should the generator Not be provided with overload protection or is their anything in NEC 2017 regarding this situation?

 

[david luchini]

NEC 2017 Section 695.6(C) and section 430.31 both says overload protection for Fire Pump is prohibited.

Neither section says overload protection for Fire Pumps is prohibited.

 

[hhsting]

Neither section says overload protection for Fire Pumps is prohibited.

I dont understand. If not those section then somewhere I heard Overload protection should not be installed for circuits Fire pump yet the generator feeding the circuits of Fire pump has internal overload protection.?? An I missing something? Generator should not have that overload protection?

 

[d0nut]

This is a motor load. There is a difference between overload protection and fault protection. The generator breaker, if sized per Table 430.52, only provides fault protection not overload protection.

 

[augie47]

I would think the generator protection is overcurrent protection as allowed in 695.4(B) {as opposed to overload}

 

[hhsting]

This is a motor load. There is a difference between overload protection and fault protection. The generator breaker, if sized per Table 430.52, only provides fault protection not overload protection.

I am Not talking about motor protection or Generator breaker. Engineer specs the breaker so it is NOT provided with generator.


I am talking about when generator was purchased it came with internal integral overload protection however its feeding Fire pump

 

[david luchini]

I dont understand. If not those section then somewhere

Don't know. Those sections don't say overload protection is prohibited for fire pumps. If you find it in another section, let us know.

 

[hhsting]

I would think the generator protection is overcurrent protection as allowed in 695.4(B) {as opposed to overload}

Please see my previous post its overload protection integral to generator. Engineer specs the breakers size and contractors install them. Generator does NOT come with breakers

 

[d0nut]

I am Not talking about motor protection or Generator breaker. Engineer specs the breaker so it is NOT provided with generator.


I am talking about when generator was purchased it came with internal integral overload protection however its feeding Fire pump

That is overload protection for the generator, not for the fire pump. They are different things. You can't provide overload protection for the fire pump.

 

[hhsting]

Don't know. Those sections don't say overload protection is prohibited for fire pumps. If you find it in another section, let us know.

See below. Can a fire pump breaker, fire pump controller have overload protection? Can generator have overload protection feeding fire pump?

 

[hhsting]

That is overload protection for the generator, not for the fire pump. They are different things. You can't provide overload protection for the fire pump.

Correct overload protection for generator integral to the generator but that generator now feeds Fire Pump. So essentially now you are providing overload protection to Fire pump power circuits. So now what generator should not have overload protection? Only generators listed to be used on fire pump needs to be used? I still dont follow

 

[tom baker]

Hasn’t this question been asked before?
We should have an HHSting FAQ section.
Fire pumps, jockey pumps, 110.26…

 

[david luchini]

See below. Can a fire pump breaker, fire pump controller have overload protection? Can generator have overload protection feeding fire pump?

No.

See below. Can a fire pump breaker, fire pump controller have overload protection? Can generator have overload protection feeding fire pump?

Generators are required to be protected against overcurrent, as d0nut noted.

 

[hhsting]

No.

Generators are required to be protected against overcurrent, as d0nut noted.

Well if first response is no then how come generator feeding fire pump requires overload protection? Its essentially like your providing overloading protection for the fire pump circuit. Wont the generator stop due to that integral overload essentially in violation of 695 and since you are saying no to first question above?

 

[don_resqcapt19]

I would think the generator protection is overcurrent protection as allowed in 695.4(B) {as opposed to overload}

Yet "overcurrent" is a defined term and includes "overload" protection.

Overcurrent.
Any current in excess of the rated current of equipment or the ampacity of a conductor. It may result from overload, short circuit, or ground fault. (CMP-10
Overcurrent Protective Device, Branch-Circuit.
A device capable of providing protection for service, feeder, and branch circuits and equipment over the full range of overcurrents between its rated current and its interrupting rating. Such devices are provided with interrupting ratings appropriate for the intended use but no less than 5000 amperes. (CMP-10)

 

[david luchini]

Well if first response is no then how come generator feeding fire pump requires overload protection? Its essentially like your providing overloading protection for the fire pump circuit.

It's not like that at all. The generator would have to be able to carry the locked rotor current of the fire pump motor indefinitely. The fire pump could be at locked rotor, and the generator would still not be overloaded.

Wont the generator stop due to that integral overload essentially in violation of 695 and since you are saying no to first question above?

No. See above.

 

[hhsting]

It's not like that at all. The generator would have to be able to carry the locked rotor current of the fire pump motor indefinitely. The fire pump could be at locked rotor, and the generator would still not be overloaded.


No. See above.

I see plans generator is sized based on load calculation of 220 which is full load amps. So when sizing the fire pump generator you have to size it according to locked rotor current? What if the generator is shared with other loads like has two breakers one for fire pump other for building loads.

 

[d0nut]

The fire pump only requires the locked rotor sizing on the normal side. The generator deals with the fire pump just like any other motor. See 695.4(B)(2)(b).

 

[hhsting]

The fire pump only requires the locked rotor sizing on the normal side. The generator deals with the fire pump just like any other motor. See 695.4(B)(2)(b).

Yes thats what I am use to but Thats not what David is saying post #16?? So then i still don’t understand generator integral overload protection will stop the generator. So then this is like providing overload protection to fire pump circuits?

 

[don_resqcapt19]

It's not like that at all. The generator would have to be able to carry the locked rotor current of the fire pump motor indefinitely. The fire pump could be at locked rotor, and the generator would still not be overloaded.


No. See above.

695.3(D) does not require the generator to be able to carry the locked rotor current indefinitely, assuming it is the alternate source of power for the fire pump.