Overcurrent protection at incoming service

[paulf2k]

Hello,

I have been a long time reader, first time poster. I have a scenario that I have run into at work that I hope some of you out there can help me with.

I am constructing a hospital and I spoke with the electrical inspector here and he raised an issue. Our 27.6kV incoming switchgear does not have overcurrent protection on the incoming loadbreak switch. This technically contradicts the electrical safety code here where "Each consumer's service, operating unit of apparatus, feeder, and branch circuit shall be provided with overcurrent protection having adequate rating and interrupting capacity in all ungrounded conductors" through circuit breakers or fuses.

In the same switchgear we have 2 additional switches, one that actually feeds the hospital and is FUSED (thus protecting the downstream feeder), and another that is empty but ready to be fused for Phase 2.

I argued with the inspector that a fuse on the incoming switch would not actually do anything but protect the internal bussing connecting the incoming switch to the fused switch ( about 2 meters worth of copper bus) since the outdoor switchgear from the Hydro company is fused as well, so the incoming feeder is protected.Although he agreed, he said I would have to put in a written request to have my situation reviewed. Also, the max current that will enter the switchgear is 84Amps at 27.6kV.

Any thoughts on further ammo to my argument? Appreciate any feedback!

 

[augie47]

See if I understand... Power Co. has switchgear outside with a fused circuit that feeds your loadbreak switch (inside) that in turns feeds your fusible distribution switchgear. Correct ?

 

[ron]

Maybe if you posted a oneline it would be helpful.

Where is the utility meter? Is it at the unfused main loadbreak switch?

Whose 27.6kV incoming switchgear is it, the Hospital or utility?

Is the unfused loadbreak switch rated to accommodate the available short circuit current?

 

[paulf2k]

Maybe if you posted a oneline it would be helpful.

Where is the utility meter? Is it at the unfused main loadbreak switch?

Whose 27.6kV incoming switchgear is it, the Hospital or utility?

Is the unfused loadbreak switch rated to accommodate the available short circuit current?

OUTDOORS 27.6 | CUSTOMER OWNED INDOOR 27.6 SWITCHGEAR
POWER CO. SWGR-------------------LOAD BREAK SW (UNFUSED)----125A FUSED LOADBREAK SWITCH
WITH 200AFUSE |

The utility meter is in another room on a 600V switchboard downstream of the switchgear. Since the load break switch is integral to the manufactured switchgear, I assume the entire thing is rated to take the available short circuit current.

Thanks!

 

[augie47]

To me, it looks compliant as is.

 

[paulf2k]

To me, it looks compliant as is.

Thank you. I have put together my response to the inspector and will let you know his response.

 

[paulf2k]

I have yet to receive a response but for further information, here is the rule I am faced with:

36-204 Overcurrent protection
(1) Each consumer?s service, operating unit of apparatus, feeder, and branch circuit shall be provided with
overcurrent protection having adequate rating and interrupting capacity in all ungrounded conductors by
one of the following:
(a) a circuit breaker;
(b) fuses preceded by a group-operated visible break load-interrupting device capable of making and
interrupting its full load rating and that may be closed with safety to the operator with a fault on the
system; or
(c) fuses, preceded by a group-operated visible break air-break switch that is capable of interrupting the
magnetizing current of the transformer installation, that may be closed with safety to the operator
with a fault on the system, and that, to prevent its operation under load, is interlocked with the
transformer?s secondary load interrupting device.
(2) Fuses shall be accessible to authorized persons only.

 

[augie47]

The NEC may not be applicable in your situation, but look at Art 230 Part VIII for a reference.