Generator + Fire Pump Controller double bonding

[gustavopeligrini]

If S1 is a Fire Pump Controller (208V 3ph), and S2 is my switchboard, does the NEC allow you to have bonding at S1 and S2?

The generator feeds the fire pump and also feeds emergency loads in a high-rise, through 2 different breakers. The ATS power the emergency loads is fed from the MDP and also the Generator. The ATS is a 3-pole, unswitched neutral. The GENSET is non-SDS, no bonding between neutral and ground.

Is this allowed? I am trying to make sense in my head of having 2 points of bonding, and it just seems wrong. I.E, if there's a fault while the generator is operating, you will have 2 paths of low impedance for the fault current? Need some help

Thanks in advance everyone.

 

[hillbilly1]

Technically, it is parallel paths, but is done that way on thousands of buildings. Had one inspector want a separate utility transformer for the fire pump, I told him good luck on getting the utility to do that!

 

[don_resqcapt19]

They are both service disconnects, and main bonding jumpers are required in all service disconnects.

 

[augie47]

In your diagram is "bond" a grounding electrode conductor/system ?
(as opposed to a main bonding jumper)

 

[gustavopeligrini]

Technically, it is parallel paths, but is done that way on thousands of buildings. Had one inspector want a separate utility transformer for the fire pump, I told him good luck on getting the utility to do that!

Good to know! Hopefully they don’t give me trouble.

They are both service disconnects, and main bonding jumpers are required in all service disconnects.

That’s what I thought too.

In your diagram is "bond" a grounding electrode conductor/system ?
(as opposed to a main bonding jumper)

They would be actual main bonding jumpers, I just threw something together in my sketch so it’s not very accurate lol.

 

[augie47]

IMO, both would also need to connect to a common grounding electrode system also.