Commercial wiring questions.

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ammklq143

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Location
Iowa
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Electrician
I'm working on a bid for a dentist office and there's a 100 amp OCPD outside and #2 alum feeding the panel inside. That should be 1/0 alum shouldn't it, since it's not a dwelling? Any thoughts as to whether or not this would have to be changed or could it stay since it's existing?

Also, above the suspended ceiling they ran NM cables all over the place. Doesn't it have to be in conduit above the suspended ceiling and again would the inspector make us change it or would it be allowed to stay since it's existing?

Thank you.
 
You would need a minimum of #1 AWG Al for 100 amps in a non-dwelling application. NM cable is not permitted above a hung ceiling. As to whether or not you'll need to rip it all out that's up to the AHJ to decide. Someone may feel that's it's grandfathered in.
 
Thanks for the reply. Would the receptacles in the patient care areas have to be hospital grade? I would guess that the reception, waiting room areas, etc. wouldn't but just wondered about the areas with the dental chairs.

infinity said:
You would need a minimum of #1 AWG Al for 100 amps in a non-dwelling application. NM cable is not permitted above a hung ceiling. As to whether or not you'll need to rip it all out that's up to the AHJ to decide. Someone may feel that's it's grandfathered in.
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ammklq143 said:
Thanks for the reply. Would the receptacles in the patient care areas have to be hospital grade? I would guess that the reception, waiting room areas, etc. wouldn't but just wondered about the areas with the dental chairs.
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I would use #1/0 AL unless you can prove that the lugs of the panel are rated at 70 deg C, in which case you could use #1 AL. As for hospital grade receptacles, that is only required in bed areas--not exam. But you will likely need medical grade wiring techniques per 517.13. And I agree that it is up to the AHJ if you have to remove all NM cable. Around here, you would.
 
ammklq143 said:
Thanks for the reply. Would the receptacles in the patient care areas have to be hospital grade? I would guess that the reception, waiting room areas, etc. wouldn't but just wondered about the areas with the dental chairs.
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Have you read through article 517 yet?

Roger
 
The wiring in the exam rooms would newly installed and would be hospital grade MC cable so it would be compliant, wouldn't it?

texie said:
Does not sound like it. HG receps that are not required connected to a wiring method that is not compliant.
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In a situation like this, regarding NM above ceiling, I usually talk to my AHJ and explain the situation and ask what he'll require.
The job I'm on now had some pre-existing Romex, but not a ton of it, only some circuits that were added within the last 5 years. Probably not done by licensed person.
He told me to make sure that my wiring cert. Detailed exactly what I was doing, and that the scope of work didn't include that stuff.
He said when he did his inspection of my work that he would check out that other stuff and would take that matter up with the business owner.
Odds are, I'll get some more work out of the project when he red flags that other stuff that wasn't part of my wiring cert. SOW.
 
As far as the romex goes above the grid ceiling, I would figure for removing completely and refeeding with MC. Not only is it more work for you and more money, but you will be able to sleep better at night. The handy man or “electrician” that pulled that Romex in there obviously did not pull a permit. So if it kills someone or starts a fire, the last person to do work in there with insurance was you. Lawyers will always go after the biggest payout and you most likely have multi-million dollar liability insurance. They don’t care if it was you or not, they just want the money.


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The electrical inspector said the romex could stay since it's pre-existing BUT if I modified anything on the circuit, the whole circuit had to be brought up to code. I just figured replacing all of it and have it done right. If someone else wants to sort through it and leave some and they get the job over me, they need the work more than I do.
 
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