Help finding code article

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I thought it was a violation to have a neutral (grounded or ungrounded) conductor dependent on a device. Apparently this is for multiwirebranch circuits only NEC 2008 300.13(B). And for 'grounded conductors only'.

I ran into a situation where they had wired an 'isolated system ' (in a hospital o.r. of all places! ) of receptacles dependent on another receptacle. I cant find a code violation, is there one, or just a bad design? I checked NFPA 99 as well too in this and found nothing!!
 

Volta

Senior Member
Location
Columbus, Ohio
I don't think that there is a restriction on that in the NEC. The orange with stripe wire is to be brought to the 'grounded' side of a 125 volt 15 or 20 amp receptacle, but as I don't know if isolation systems are ever made for MWBC, I don't think it is a violation to use the device for the connection. Not a great design . . . agreed.
 

Chamuit

Senior Member
Location
Texas
The commentary in the handbook say that the requirement does not apply to individual 2-wire circuits or other circuits that do not contain a grounded conductor.

We started doing this on all circuits when the AFCI's became a requirement. Hots and neutrals. Seemed to cut down on the troubles with AFCI breakers.
 

e57

Senior Member
There are a few other places where 300.13(B) is referenced (like 230.46) but yeah - only required on neutrals of multi-wire circuits... Otherwise back-stabbing or use of the terminals is OK - even looping the conductor on to - then off of the terminals. Is it allowed yes - is it bad design IMO no - you should not have to remove a device live anyway.... Back-stabbing is not a good idea since the contact design was never any good in the first place. But terminal connections if made properly should be just as good as a wire nut. And looping around the terminal with an unspliced conductor has not changed the conductivity of it in any way substantial.
 

roger

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Along with the other replies, since there is no neutral in an Isolated Power System and both conductors are phase wires, losing or opening one hot conductor is no different than loosing or opening the other.

Roger
 
Along with the other replies, since there is no neutral in an Isolated Power System and both conductors are phase wires, losing or opening one hot conductor is no different than loosing or opening the other.

Roger
This is true, but from my experience in working in some hospitals, believe it or not they can be rough in using some receptacles in operating rooms. It just seems like bad practice to 'daisy chain' these emergency power receptacles. Especially when EE go painstakingly to ensure there are enough circuits of both normal power and emergency for the operation.

I Have seen receptacles go bad when they were daisy chained and cause the rest of the good receptacles downstream from it loose power.

I think it should not be allowed in operating rooms in hospitals. ;)
 

e57

Senior Member
I Have seen receptacles go bad when they were daisy chained and cause the rest of the good receptacles downstream from it loose power.

I think it should not be allowed in operating rooms in hospitals. ;)
A bad splice could do te same...

Write a code... Submit it. Wait - follow up with substantiation - wait. Get the exothermic welding or wire nut manufactures to help you out - they have more clout and resources than you - re-submit next cycle - wait - you get the idea.... ;)
 
A bad splice could do te same...

Write a code... Submit it. Wait - follow up with substantiation - wait. Get the exothermic welding or wire nut manufactures to help you out - they have more clout and resources than you - re-submit next cycle - wait - you get the idea.... ;)
Maybe I will do that for operating rooms. In hospitals operating rooms are about reducing risk. And Yes a bad splice can cause a problem too, however it seems that the 'daisy' chained receptacles I've run into tend to be more problems than those that are parralled. ;)

Not to mention from NEC 2008 210.21(B)(2) says where two or more receptacles or outlets, a receptacle shall not supply a total cord and plug connected load in excess of the maximum specified in table 210.21(B)(2). A 20 amp receptacle has a maxium load of 16 amps even under 3 hrs (continuous load) compared to the branch circuit rating (20 amp breaker) that can tolerate it for up to 2hrs 59minutes for anything over 16 amps ;) . It's not just talking about something 'directly' plug into it, but the 'tabs' (screw terminals) as well.

When you daisy chain, you increase the chance/risk of violation. If you had 8 duplex receptacles daisy chained and each one had just over 2 amps of a load (say total of 17 amps), the first receptacle in the chain that feeds everything else would see more than 16 amps compared to the rest of the others down stream, creating the violation.

Not to mention more use/abuse from the current on the first receptacle compared to the others down stream, you want to help even out the loads on that circuit and devices especially in hospitals.

If you really understood the requirements and restriction and annual testing of receptacles as per NFPA 99 I believe you would see this differently. :)
 

roger

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Brother, you have a great imagination. :grin:

Roger
 
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