Low voltage equipment with medium voltage same room and working space other issues

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hhsting

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Glen bunie, md, us
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Junior plan reviewer
Attached sketch show in electrical room following items:

1. 13.2kV 125A fused switch,
2. 2000kva 13.2kv to 480/277V transformer,
3. 3000A 480/277V switchboard,
4. 300kva 480V to 208/120V transformer,
5. 225kva 480V to 208/120V transformer
6. Low voltage less than 600V panelboards fed from swbd #3 DPR, RPB, EDMP, LPB
7. Standby generator ATS


My concern is mainly 110.26 working space and anything that relates to 13.2kV transformer


Following questions:

1. NEC 2017 110.26)A)(5) requires separation of high voltage equipment this means their has to be some separation between 13.2 kV and the 480V, 208V equipment? Correct or incorrect?

2. Is their anything in NEC 2017 section 110.26 or 450 that requires 2000KVA 13.2kV to 480/277V transformer to be in separate vault Not in same room?

3. Distances are marked on the sketch is their anything else I am missing that is not per NEC code? Clearance wise or being separate wise or anything else?


94d5ece9743fc2b592da40ed7987c843.jpg
 
Access to egress is a problem. You would potentially have to get around and past other high/medium voltage equipment to get out of the room. Distance, egress space between equipment would need to be basically doubled what ever working space requirement of the individual peice of equipment if you must pass between the equipment to egress the space.
Is this an existing room that other equipment being added to? What is existing and new?
 
The separation/isolation is already there. This rule means like in the case of open bus or bare wiring. It has to do with insulation.

Within MV switchgear it is normally built as a bare minimum with the instrumentation and controls separate from the equipment, and in most equipment the terminations and equipment are separate. In transformers except up on poles the primary and secondary compartments are separate.

An example if a problematic area is when you may have remote signals to/from a PLC and the most convenient path is through the switchgear so then you have to use a raceway and/or routing and tie wrapping everything to avoid any possible chance of medium/low voltage faults. The last thing anyone wants is dealing with 13.5 kV on control power wiring.
 
Fred B said:
Access to egress is a problem. You would potentially have to get around and past other high/medium voltage equipment to get out of the room. Distance, egress space between equipment would need to be basically doubled what ever working space requirement of the individual peice of equipment if you must pass between the equipment to egress the space.
Is this an existing room that other equipment being added to? What is existing and new?
Click to expand...

The room is existing and the 13.2kV switch is existing. Other than that everything else is new
 
paulengr said:
The separation/isolation is already there. This rule means like in the case of open bus or bare wiring. It has to do with insulation.

Within MV switchgear it is normally built as a bare minimum with the instrumentation and controls separate from the equipment, and in most equipment the terminations and equipment are separate. In transformers except up on poles the primary and secondary compartments are separate.

An example if a problematic area is when you may have remote signals to/from a PLC and the most convenient path is through the switchgear so then you have to use a raceway and/or routing and tie wrapping everything to avoid any possible chance of medium/low voltage faults. The last thing anyone wants is dealing with 13.5 kV on control power wiring.
Click to expand...

What exactly does exposed live parts mean? If you are doing maintenance in equipment you need to open the door and can have exposed live parts. The exposed live parts apply to switchboard, panelboards when doing working space 110.26(A). How come it wont apply here?


Does not the rule mean one need to separate 480/277V switchboard, panelboard, transformer and 208/120V switchboard from the 13.2kV switch and 13.2kv transformer? I dont follow
 
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There is nothing special required. It is a very common practice to have line-up that includes a medium voltage switch, a medium voltage transformer and the 480 volt switch gear all together.
As long as each piece of equipment has the workspace that is required by the code and you have the egress required by the code, you are good.
 
don_resqcapt19 said:
There is nothing special required. It is a very common practice to have line-up that includes a medium voltage switch, a medium voltage transformer and the 480 volt switch gear all together.
As long as each piece of equipment has the workspace that is required by the code and you have the egress required by the code, you are good.
Click to expand...

Ok but the below link seems to indicate that their needs to be separation between low voltage and high/medium voltage equipment. In below link it is 3 hours rated wall??? How does one explain the new code section NEC 2017 section 110.26(A)(5)?:

110.26(A)(5) Separation from High-Voltage Equipment.

Switchgear in the far room operates at 12,470 volts while equipment in the closest room operates at 480 volts. The 3 hour barrier and fire rated door creates the suitable partition required by the new code section. Are there any other issues to be concerned about in the image?
www.electricallicenserenewal.com
 
hhsting said:
Ok but the below link seems to indicate that their needs to be separation between low voltage and high/medium voltage equipment. In below link it is 3 hours rated wall??? How does one explain the new code section NEC 2017 section 110.26(A)(5)?:

110.26(A)(5) Separation from High-Voltage Equipment.

Switchgear in the far room operates at 12,470 volts while equipment in the closest room operates at 480 volts. The 3 hour barrier and fire rated door creates the suitable partition required by the new code section. Are there any other issues to be concerned about in the image?
www.electricallicenserenewal.com
Click to expand...
That only applies to the old style installations where you could walk up to and grab the exposed energized parts without first having remove a cover or open an enclosure door.
 
Fred B said:
Access to egress is a problem. You would potentially have to get around and past other high/medium voltage equipment to get out of the room. Distance, egress space between equipment would need to be basically doubled what ever working space requirement of the individual peice of equipment if you must pass between the equipment to egress the space.
Is this an existing room that other equipment being added to? What is existing and new?
Click to expand...

But both egress doors are within 25 feet in relation to the 480/277V Swbd? Still require double working space?
 
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