Fire Pump Disconnect Switch

[Grouch]

Hey Gang,
Here's another point of confusion for me :ashamed1::

I attached a link to the NYC amendments for the 2008 NEC (hopefully you can just click on the link):
www.nyc.gov/html/dob/downloads/bldgs_code/electrical_code_local_law_39of2011.pdf

If you scroll down to page 72 (article 695 for fire pumps), under 695.4(A) Exception 2, it says if you have a limited service fire pump connected to both utility and an emergency generator, your disconnecting means does not need to be a service disconnecting means (so you can use a breaker on a panel to feed the limited service fire pump).

If you scroll down to page 73, under 695.4(B)(3) Exception, it says that your disconnecting means for fire pumps AND limited service fire pumps connected to emergency generators does not need to be service equipment (so I'm assuming you can again use a breaker on a panel to feed the pumps). Do they mean to say fire pumps and limited service fire pumps that are ONLY connected to emergency generators with no connection to a utility service? why wouldn't they mention 'utility service' the way they did above on page 72? If they also meant utility service (together with the emergency generator), why wouldn't the Fire Pump have been mentioned in Exception 2 on page 72 (as I wrote above for Limited Service Fire Pumps)?

Thanks! (hope that wasn't too confusing)

 

[infinity]

Hey Gang,
Here's another point of confusion for me :ashamed1::

I attached a link to the NYC amendments for the 2008 NEC (hopefully you can just click on the link):
www.nyc.gov/html/dob/downloads/bldgs_code/electrical_code_local_law_39of2011.pdf

If you scroll down to page 72 (article 695 for fire pumps), under 695.4(A) Exception 2, it says if you have a limited service fire pump connected to both utility and an emergency generator, your disconnecting means does not need to be a service disconnecting means (so you can use a breaker on a panel to feed the limited service fire pump).This means if you have a generator backup then the normal source for the LSFP does not need to be a service disconnect and can come from a normal panel or distribution board.

If you scroll down to page 73, under 695.4(B)(3) Exception, it says that your disconnecting means for fire pumps AND limited service fire pumps connected to emergency generators does not need to be service equipment (so I'm assuming you can again use a breaker on a panel to feed the pumps). Do they mean to say fire pumps and limited service fire pumps that are ONLY connected to emergency generators with no connection to a utility service? why wouldn't they mention 'utility service' the way they did above on page 72? If they also meant utility service (together with the emergency generator), why wouldn't the Fire Pump have been mentioned in Exception 2 on page 72 (as I wrote above for Limited Service Fire Pumps)? I'm still pondering this one.

Thanks! (hope that wasn't too confusing)

Let me think about this.

 

[Grouch]

Let me think about this.

Yeah tricky language :?

 

[Grouch]

... just replying to bring this thread back up. any thoughts? :ashamed1:

 

[Grouch]

Reading it again, I have to assume that the language on page 73 is saying just that... that the exception only applies to fire pumps and LSFP's connected to emergency generators. It did not mention any connection to utility... so this applies only for FP's and LSFP's that are only connected to a generator (no utility service is present, so I'm assuming in these cases the generator is the prime power source).

I drew up the following diagrams based on these rules (pages 72 and 73), as to how fire pumps and LSFP's can be connected to utility (U) and generators (G). These are just simplified wiring diagrams. Any feedback is welcome!

 

[infinity]

Sections 695.4(B)(1)&(2) outline the requirements for the disconnecting means and OCPD for both the utility and generator supplies.

The confusion lies in the exception to 695.4(B)(3) which seems to contradict the requirement in 695.4(A) for the fire pump disconnecting means which says "fire pump shall be supplied from a single dedicated service disconnecting means".