Large equipments electrical room

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hhsting

Senior Member
Please see attached sketch shows electrical room with following equipment:

1. 208V three phase 4000A switchboard
2. 480V three phase 4000A switchboard
3. Rack equipment with panelboards and xfmr
4. 3000A trough with cts and 6 disconnects


The question i have are following:

1. Would the 4000A 480V three phase switchboard in compliance with 110.26(C)(2)? It has two exits but they are not at each end of working space and NEC 2017 section 110.26(C)(2)(b)(a) would not apply

2. Would the 4000A 208V three phase switchboard in compliance with NEC 2017 section 110.26(C) or not?

3. Would the 3000A trough with disconnect fall under NEC 2017 Section 110.26(C) large equipment or not?

1b6e0288ff4b720e7570b6b24e7369b5.jpg
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Please see attached sketch shows electrical room with following equipment:

1. 208V three phase 4000A switchboard
2. 480V three phase 4000A switchboard
3. Rack equipment with panelboards and xfmr
4. 3000A trough with cts and 6 disconnects


The question i have are following:

1. Would the 4000A 480V three phase switchboard in compliance with 110.26(C)(2)? It has two exits but they are not at each end of working space and NEC 2017 section 110.26(C)(2)(b)(a) would not apply

2. Would the 4000A 208V three phase switchboard in compliance with NEC 2017 section 110.26(C) or not?

3. Would the 3000A trough with disconnect fall under NEC 2017 Section 110.26(C) large equipment or not?
1) I would not accept an egress path that requires the worker to exit on the back side of the equipment that is experiencing an arcing burndown. If the wall would continue to the end of the equipment, I would find the installation in compliance.
2) that appears to be compliant, assuming the 480 volt pull box is wall mounted with 7' or more from the floor to the bottom of the pull box. If that is floor mounted, or below 7' AFF, I would see that as obstructing the egress path for the equipment.
3) the rule does not apply to multiple separate pieces of equipment.

These answers are MY opinion on the code requirements based on the information provided.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Excellent answer !!!!!!
I would not have thought about extending the wall but certainly makes sense.
 
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