We currently are working on a fire pump/generator install for a high rise building in NJ (22 stories). There is an existing fire pump being fed from a switch in the main switch gear which is being direct replaced. The new fire pump was designed to be tapped ahead of the main switch and CT's via Coated MC and routed to the new Fire Pump CT Cabinet/disconnect on the other side of the electric room. After the CT/Disconnect the MC Cable switches over to Vitalink Cable routed through the non fire rated common space areas. The town approved the design, however up PSE&G's inspection for the shut down they are requesting the Coated MC to be change to RGS. The engineer seems to believe that if we tap on the other side of the CT's, still ahead of the main switch that this will remove the requirement for RGS from PSEG. This has gone pretty far down the rabbit hole over the last month while the engineer tries to come up with a solution to avoid a measly $5K change order to satisfy the utility requirement. Internally, we believe the correct thing to do is satisfy the utility requirement. Is the engineer correct that by tapping on the outgoing side of the CT's and sharing the existing metering should eliminate the RGS requirement and allow the Coated MC to remain? Any insight is appreciated.
FIRE PUMP FEEDER REQUIREMENTS FOR BUS TAP
- Thread starter thahn1
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Joethemechanic
Senior Member
- Location
- Hazleton Pa
- Occupation
- Electro-Mechanical Technician. Industrial machinery
I don't see any real change functionally by moving to the load side of the CTs. It's not like it's going to change available fault current or anything. I guess they want RGS with RHH? I can see that as being a lot better at preventing a fault current from happening in the first place.
5k can't be worth fighting about for too long
5k can't be worth fighting about for too long
Agreed. Regardless of whether the tap is done before or after the CT's I still expect the utility company to hold there spec. The only thing I can think of that would override the utilities jurisdiction and allow the feeder to remain as Coated MC would be the fact that you are eliminating the second CT Cab and Meter before the FP Disconnect. Unfortunately these guidelines are not clarified in the NJ PSE&G handbook, only the Long Island, NY PSE&G guidelines. Ultimately it's not our decision as the EC, just waiting to see how it plays out and get other's input on the situation in the meantime.
Joethemechanic
Senior Member
- Location
- Hazleton Pa
- Occupation
- Electro-Mechanical Technician. Industrial machinery
Just curious, how many horsepower? What's the locked rotor current?
I did some diesel powered ones in Philly, but that had to be a long time ago, because if I remember right they were 4-53 Detroit Diesel powered. I can't remember why they weren't electric. Probably not enough power available
I did some diesel powered ones in Philly, but that had to be a long time ago, because if I remember right they were 4-53 Detroit Diesel powered. I can't remember why they weren't electric. Probably not enough power available
PD1972
Member
- Location
- New York (2017 NEC)
- Occupation
- engineer
I personally don't think the engineer's original design is code compliant to begin with. You can't use coated MC cable between your switchgear (probably a switchboard) tap section to your fire pump disconnect.
The supply conductors on the line side of your fire pump disconnect (which I assume has overcurrent protection) need to be installed as service entrance conductors. In essence, fire pump supply conductors have no overcurrent protection ahead of them so the requirements are similar to those of service entrance conductors (this is also stated in 695.6(A)(1)). Fire pump controllers/ATSs are listed as suitable for use as service entrances for this reason.
Service entrance conductors need to be routed "outside of the building" as they are unprotected. To be considered "outside the building" while technically still inside the building would require concrete or brick encasement per 230.6(1) or (2). There is an exception to this added in NEC 2020 that only applies to within the fire pump room. Based on your description of the design, it appears that the fire pump room is somewhere else so this exception doesn't apply.
Tangent aside, to answer your question - no, changing where the tap is located won't make coated MC cable acceptable. The engineer is misapplying 695.6(D), which only applies to wiring from the fire pump controller to the actual pump.
The supply conductors on the line side of your fire pump disconnect (which I assume has overcurrent protection) need to be installed as service entrance conductors. In essence, fire pump supply conductors have no overcurrent protection ahead of them so the requirements are similar to those of service entrance conductors (this is also stated in 695.6(A)(1)). Fire pump controllers/ATSs are listed as suitable for use as service entrances for this reason.
Service entrance conductors need to be routed "outside of the building" as they are unprotected. To be considered "outside the building" while technically still inside the building would require concrete or brick encasement per 230.6(1) or (2). There is an exception to this added in NEC 2020 that only applies to within the fire pump room. Based on your description of the design, it appears that the fire pump room is somewhere else so this exception doesn't apply.
Tangent aside, to answer your question - no, changing where the tap is located won't make coated MC cable acceptable. The engineer is misapplying 695.6(D), which only applies to wiring from the fire pump controller to the actual pump.
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