Redundant grounding

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electricalist

electricalist

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dallas tx
As I survived my first health care facility I have questions.
A critical circuit that requires a metal raceway. On the underground pvc was ran underground to feed nurses stations. I believe ridged should be used there or would pvc be ok as long as 2 wire type grounds were used?

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electricalist said:
As I survived my first health care facility I have questions.
A critical circuit that requires a metal raceway. On the underground pvc was ran underground to feed nurses stations. I believe ridged should be used there or would pvc be ok as long as 2 wire type grounds were used?

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Get ready to run some metal raceway, whether in the ground or an alternate route - Can't recall the exact 517 section but it is fairly clear you must have a metal raceway or other wiring method that itself qualifies as an equipment grounding conductor as well as a wire type grounding conductor within that raceway or other method.

Keep in mind this only applies to branch circuit wiring, if your PVC is for feeders you are ok.
 
I agree.
I have another question if you dont mind.
Can the generator , having 2 breakers, 1 for each ATS be tapped from one feeder to add a 3rd ATS?
The designer one lined critical and life safety on the same ATS. Since that isnt correct they one lined a tap on the feeder so the it splits to ATS X to critical and to ATS O to life safety.
Both feed from one breaker on the generator.
I feel thats a bad move.
If its trips they lose both which was the original problem.

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electricalist said:
I agree.
I have another question if you dont mind.
Can the generator , having 2 breakers, 1 for each ATS be tapped from one feeder to add a 3rd ATS?
The designer one lined critical and life safety on the same ATS. Since that isnt correct they one lined a tap on the feeder so the it splits to ATS X to critical and to ATS O to life safety.
Both feed from one breaker on the generator.
I feel thats a bad move.
If its trips they lose both which was the original problem.

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Again without looking I believe it can depend on the capacity of the generator. I know I had a small capacity (maybe 65kVA - but small is not same for everyone either but 100kVA seems to stick in my mind as the limit here) unit in a small town hospital one time that only had a single breaker and single transfer switch supplied all the required branches.
 
I was thinking 150 or smaller could feed all ATS s 150 and up needs a 2nd.
Im not confident on my understanding of what panels can be on the same ATS .

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electricalist said:
I was thinking 150 or smaller could feed all ATS s 150 and up needs a 2nd.
Im not confident on my understanding of what panels can be on the same ATS .

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150 may be correct. The installation I had was a switchboard right after a single ATS, but then a switch for each required branch - and keep from interconnecting wrong circuits to wrong branch from there on. This was an existing generator, ATS and switchboard, - I was making some modifications to what loads were connected and nearly starting over from each branch level, but pretty sure we had figured what was ahead of my work was basically compliant had we been installing it new.
 
electricalist said:
In youre opinion when we say metal raceway or cable assembly that qualifies. Would HCF MC qualify?

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Yes MC is a cable assembly, and the HCF varieties have both a sheath that is a qualifying EGC as well as a wire type EGC inside.
 
electricalist said:
When reading 517. HCF / ac cable do qualify but only in limited situations in place of conduit. Correct?

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Limitations would be IAW art 320 AC cable article limitations.

Used to be HCF cable was AC cable. When they started making MC-AP or other equivalents, I think is when you started seeing HCF in an MC cable.
 
electricalist said:
When reading 517. HCF / ac cable do qualify but only in limited situations in place of conduit. Correct?

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If it was a critical branch circuit as mentioned in the first post it should not be in flex. 517.30 (c)(3)
 
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