pnunley
Member
- Location
- Beltsville, MD USA
I was working in an OR in a hospital where I was troubleshooting breakers tripping intermittently for no apparent reason. Upon taking the cover off of the panelboard fed from a 120volt isolation transformer I noticed two items of concern to me.
1. The electrician installed two circuits in each conduit feeding receptacles using a common neutral. By definition this is not a multiwire branch circuit.
2. The IG receptacles were fed with two grounds. One from the isolated ground bar and one from the equipment ground bar. Both were tied together at each receptacle location.
It is my understanding that there is the possibility of an overload on the neutral in #1. The purpose of the IG is defeated by tying them together at the device location in #2. Am I correct in both assumptions?
Also, considering the situation is there any reason that they are getting nuisance tripping on the IG receptacle circuits?
Thank you!
1. The electrician installed two circuits in each conduit feeding receptacles using a common neutral. By definition this is not a multiwire branch circuit.
2. The IG receptacles were fed with two grounds. One from the isolated ground bar and one from the equipment ground bar. Both were tied together at each receptacle location.
It is my understanding that there is the possibility of an overload on the neutral in #1. The purpose of the IG is defeated by tying them together at the device location in #2. Am I correct in both assumptions?
Also, considering the situation is there any reason that they are getting nuisance tripping on the IG receptacle circuits?
Thank you!