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Swimmer
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Discussion Starter · #1 ·
One of the Mike Holt forums said that "dedicated circuit" is a trade term rather than a term defined in the NEC. I did not see this term in the index of my hardcopy NEC.

That being said, I'm working on an Automatic DVD rental machine in a super market. This is a concession deal. The machine is not owned or operated by the super market. The machine is supposed to be on a dedicated circuit. The breaker serves only the DVD machine. However, the neutral is shared with 2 other breakers on the 2 other phases of the 208V / 120V panel.

So would this still be considered a dedicated circuit?

Problem history.
The power strip in the machine was blown when I arrived.
I plugged in a new one, with no load, and it blew.
I made a Peak-Hold measurement with my DMM and got 187V. Should be 120V. This was momentary and I could not reproduce it.

I suspect an open neutral in the store wiring. I anticipate that there will be some controversy as to what constitutes a dedicated circuit and both the super market and the DVD machine company will be asking me this question.
 

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My company purchased an AT&T cell tower for our remote location. I was required to provide two 20A "dedicated circuits" to the equipment as part of the deal. I didn't see it as a code question but more of a question of reliable service to their equipment. The people that own that DVD machine don't want it on the same circuit as the breakroom microwave, for example.


I guess that's obvious, sorry..but yeah I pulled separate neutrals for both of them.
 

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To me what you have there meets the definition of "dedicated circuit". The ungrounded conductor is not used by anything else so you have its full capacity to deliver current available. Sure a dedicated neutral might have prevented this situation(a proper original installation would also have) but if the machine vendor wanted a dedicated neutral that's something they should specifically have asked for.

Millions of commercial buildings everywhere share neutrals for every general purpose circuit. I think the neutral is in need of investigating. Not being able to reproduce the 187v you were getting at the receptacle might have to do with one of the other two circuits on the neutral being a cycling load.
 

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Swimmer
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Discussion Starter · #6 ·
A dedicated circuit is just a circuit you pull strait from the panel to the machine with no other loads.

Article 100.

Branch Circuit, Individual. A branch circuit that supplies only one utilization equipment.
It sounds like I have a "dedicated" or "branch circuit individual". I anticipate that the super market and the DVD rental company may argue about who pays for me to run down the open neutral based on the fact that the circuit was supposed to dedicated.
 
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