Twist

[hhsting]

Well no one knows?


I also find this very interesting too the exception below too

 

[david luchini]

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.

I didn't see any mention of another source...just a generator.

 

[david luchini]

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?

Why would the generator stop if it's not overloaded?

 

[hhsting]

I didn't see any mention of another source...just a generator.

See post #1 says somewhere “backup generator”.

Yes the generator is the alternate source primary source is the utility.

 

[david luchini]

See post #1 says somewhere “backup generator”.

Yes the generator is the alternate source primary source is the utility.

You didn't say anything about a normal source and an alternate source.

If the generator is an alternate source, why are you asking about overload at all?

 

[hhsting]

You didn't say anything about a normal source and an alternate source.

If the generator is an alternate source, why are you asking about overload at all?

That alternate source back up generator that has integral overload feeds the fire pump as backup.

Fire pump power circuits or fire pump are not allowed to have overload. When utility fails generator turns on you are essentially providing fire pump power circuits overload protection thru generator integral overload protection. That would violate 695 since it would stop the generator when under overload?

 

[david luchini]

Fire pump power circuits or fire pump are not allowed to have overload.

695.4(B)(2)(b) says the generator breaker feeding the fire pump shall be sized for short circuit only. There's no overload protection.

That would violate 695 since it would stop the generator when under overload?

If the fire pump overloads the generator, then you haven't sized the generator properly.

 

[hhsting]

695.4(B)(2)(b) says the generator breaker feeding the fire pump shall be sized for short circuit only. There's no overload protection.


If the fire pump overloads the generator, then you haven't sized the generator properly.

Your saying that the total demand and connected load calculation performed when sizing the generator would be incorrect somewhere if the generator overload protection stops the generator?

 

[don_resqcapt19]

Your saying that the total demand and connected load calculation performed when sizing the generator would be incorrect somewhere if the generator overload protection stops the generator?

can you expand on exactly what type of generator overload protection you are talking about

 

[hhsting]

can you expand on exactly what type of generator overload protection you are talking about

I will get the submittal or more info on that from engineer but all I know right now is from phone conversation is that it is overload integral to the generator and manufacturer factory provided.

This is different from the generator for breakers because generator is not going to come with breaker but the engineer is going to spec the size of the breakers and contractor is going to install it once generator has arrived from factory

 

[d0nut]

I will get the submittal or more info on that from engineer but all I know right now is from phone conversation is that it is overload integral to the generator and manufacturer factory provided.

This is different from the generator for breakers because generator is not going to come with breaker but the engineer is going to spec the size of the breakers and contractor is going to install it once generator has arrived from factory

The generator overload protection is included by the manufacturer to protect the generator in case something else fails. It protects the engine and the alternator, and is integral to the generator, and has nothing to do with your fire pump. You cannot omit this overload protection, and even if you somehow could, it wouldn't change anything for your fire pump because the generator is incapable of producing more power that what the overload protection would have been set to. It is a mechanical limitation of the generator. Without the generator overload protection, the engine would still stall or the alternator magnetic field would collapse if you overloaded the generator too severely.

Stop trying to re-engineer manufactured equipment through your plan review process.

 

[hhsting]

The generator overload protection is included by the manufacturer to protect the generator in case something else fails. It protects the engine and the alternator, and is integral to the generator, and has nothing to do with your fire pump. You cannot omit this overload protection, and even if you somehow could, it wouldn't change anything for your fire pump because the generator is incapable of producing more power that what the overload protection would have been set to. It is a mechanical limitation of the generator. Without the generator overload protection, the engine would still stall or the alternator magnetic field would collapse if you overloaded the generator too severely.

Stop trying to re-engineer manufactured equipment through your plan review process.

Its alternate source to Fire Pump so its concerning NEC says overload not be provided for Fire Pump while generator has integral overload. Speaking of what you posted See post #21. Exception posted What do you think?

Also, did you see post #27 David says if you size the generator right then generator integral overload protection would not stop the generator.

So if the demand and connected load cals is done right then generator integral protection would not even stop the generator?

 

[d0nut]

See post #21. What do you thin?

Also, did you see post #27 David says if you size the generator right then generator integral overload protection would not stop the generator.

So if the demand and connected load cals is done right then generator integral protection would not even stop the generator?

The fire pump would not overload the generator under normal operating conditions. If the fire pump is plugged and drawing locked rotor current, the generator would typically be overloaded and shut down.

 

[hhsting]

The fire pump would not overload the generator under normal operating conditions. If the fire pump is plugged and drawing locked rotor current, the generator would typically be overloaded and shut down.

The alternate source generator has 2 breakers: one building loads and second feeds fire pump.

Generator is not suppose to size to handle fire pump locked rotor current anyways correct NEC 2017 section 695 somewhere correct?

 

[hillbilly1]

The alternate source generator has 2 breakers: one building loads and second feeds fire pump.

Generator is not suppose to size to handle fire pump locked rotor current anyways correct NEC 2017 section 695 somewhere correct?

Don has already answered this question. The generator must only provide enough current to start and run the generator plus all other loads on generator. Load shedding is allowed if the other loads are optional, such as by a shunt trip breaker tied to the fire pump controller.

 

[hhsting]

Don has already answered this question. The generator must only provide enough current to start and run the generator plus all other loads on generator. Load shedding is allowed if the other loads are optional, such as by a shunt trip breaker tied to the fire pump controller.

Other building loads are life safety, legally required and optional combination of all three with of course separate three ATS down stream.

I understand that generator is not required to size based on Fire Pump locked rotor current. If the engineer decides to size generator based on Fire Pump Locked Rotor Current then the integral overload protection inside generator would not stop the generator even in locked rotor current condition correct or incorrect?

 

[d0nut]

Other building loads are life safety, legally required and optional combination of all three with of course separate three ATS down stream.

I understand that generator is not required to size based on Fire Pump locked rotor current. If the engineer decides to size generator based on Fire Pump Locked Rotor Current then the integral overload protection inside generator would not stop the generator even in locked rotor current condition correct or incorrect?

If the generator is designed to not be overloaded in that condition, why would you expect the generator overload protection to stop the generator?

 

[hhsting]

If the generator is designed to not be overloaded in that condition, why would you expect the generator overload protection to stop the generator?

I dont know. I am not sure about integral overload protection typically would do

 

[hillbilly1]

Other building loads are life safety, legally required and optional combination of all three with of course separate three ATS down stream.

I understand that generator is not required to size based on Fire Pump locked rotor current. If the engineer decides to size generator based on Fire Pump Locked Rotor Current then the integral overload protection inside generator would not stop the generator even in locked rotor current condition correct or incorrect?

Correct, along with the other loads running concurrently. If the engineer is worried about the fire pump taking out the life safety on locked rotor, the pump can be put on the proper ocp in the generator. Must be a government building if they are wasting the money on that size of generator. If it is a diesel generator, oversizing it will reduce its life due to wet stacking.

 

[roger]

Stop trying to re-engineer manufactured equipment through your plan review process.

Very good advice.

Roger