Double Ended Switchgear Neutral and Grounding Bonding

[faresos]

If you have a two double ended switchgear with two tie breakers, each fed from a utility transformer (480/277- Secondary). The tie in conductors between the gears have neutral and ground conductors. I was told by the contractor the bonding of the neutral and ground should only happen at one of the switchgear not both. Is this true? I always bond them at the first disconnecting means which in this case each gear. Any thoughts? thanks,

 

[brian john]

You need to check the drawings and specifications for the switchboard. If equipped with GFPE and you ground improperly you can affect the operation of the GFPE.

But in my expierence this is a solid neutral switchboard and should be grounded in one location and that location is critical.

 

[weressl]

If you have a two double ended switchgear with two tie breakers, each fed from a utility transformer (480/277- Secondary). The tie in conductors between the gears have neutral and ground conductors. I was told by the contractor the bonding of the neutral and ground should only happen at one of the switchgear not both. Is this true? I always bond them at the first disconnecting means which in this case each gear. Any thoughts? thanks,

A double ended substation would have TWO main breakers, one for each transformer and ONE tie. The normal control configuration is that when one main opens - due to loss of the transformer - the tie would close. The paralleling of the transformers is avoided, mainly so that the gera does not have to be rated for fault contribution from both and the arc-flash hazard is kept to a manageable level. Each transformer neutral would need to be grounded either at the transformer or at the bus in the gear. Never seen a 4 pole tie breaker and the neutral bar was always continuous, then again most of my systems are resistance grounded so I don't use the neutral.