I noticed something I had never had experience with on a service call. I noticed opened a fuel panel inside a gas stations The panel was labeled fuel with a 2 pole main breaker. One side is 120v and other side is neutral on main breaker. I suspect so you can isolated any current going back to dispenser on neutral There is a contactor being used ahead of panel being used to for E stop to kill power to panel during emergency. is this a common way to feed power to fuel dispensers. I had never had opportunity to work on anything for fuel dispensers so I am interesred to know if this is common practice.
swiched neutral
- Thread starter mannyb
- Start date
- Status
514.11 Circuit Disconnects.
(A) General. Each circuit leading to or through dispensing
equipment, including all associated power, communications,
data, and video circuits, and equipment for remote
pumping systems, shall be provided with a clearly identified
and readily accessible switch or other approved means,
located remote from the dispensing devices, to disconnect
simultaneously from the source of supply, all conductors of
the circuits, including the grounded conductor, if any.
Single-pole breakers utilizing handle ties shall not be
permitted.
(A) General. Each circuit leading to or through dispensing
equipment, including all associated power, communications,
data, and video circuits, and equipment for remote
pumping systems, shall be provided with a clearly identified
and readily accessible switch or other approved means,
located remote from the dispensing devices, to disconnect
simultaneously from the source of supply, all conductors of
the circuits, including the grounded conductor, if any.
Single-pole breakers utilizing handle ties shall not be
permitted.
oldsparky52
Senior Member
- Location
- Wilmington, NC USA
So basically the question is can you feed a panel with L1 (or L2) and Neutral to the busbar and then use a standard 2-pole breaker instead of the switched neutral breaker.
I have been asking this question for 2 decades and no one would ever give a simple answer. Personally, I don't see anything wrong with this (but I've never done it).
I have been asking this question for 2 decades and no one would ever give a simple answer. Personally, I don't see anything wrong with this (but I've never done it).
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
So how do the 120V circuits get their neutral? Does the circuit neutral go to the stabs that tie to the main where the neutral lands? And are they the same size OCP as the hot?
ETA: After thinking about it, are the breakers all 2-pole with hot on one and neutral on the other?
ETA: After thinking about it, are the breakers all 2-pole with hot on one and neutral on the other?
mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
Its a myth that a neutral conductor is at ground potential. You will have voltage drop on the service neutral in addition to voltage contributions from the utilities MGN which is typically tied into the secondary neutral. Further past the main panel you will have voltage drop across the feeder neutral raising it up to several volts above the EGC or anything bonded to the GEC. Higher readings relative to remote earth- any metal in contact with earth which is not connected to the building's EGC or GEC.
And of course if the neutral breaks at any point up to 120 or 277 volts could be measured to earth.
As such its a good idea to disconnect the neutral where it could spark to anything grounded.
And of course if the neutral breaks at any point up to 120 or 277 volts could be measured to earth.
As such its a good idea to disconnect the neutral where it could spark to anything grounded.
mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
Typically its a two pole breaker with a pig-tail. Two slots but the breaker only grabs one stab.
oldsparky52
Senior Member
- Location
- Wilmington, NC USA
The bus has one grounded and one ungrounded conductor. So for a 120V circuit you use a 2-pole breaker and now when the breaker is turned off it breaks the neutral, and since a neutral overload would trip the breaker for the hot it is okay to have OCP on the neutral of the circuit.
Keeps you from having to use the seriously overpriced switched neutral breaker and puts all the dispensers in one panel for easy disconnect in an emergency. I always wanted to do it but never brave enough to chance an AHJ getting weird about it.
oldsparky52
Senior Member
- Location
- Wilmington, NC USA
I also tried to get panel manufacturer (SQ D I-line)) to say that supplying a 3-phase panel with single-phase (bus would be L1,N,L2) then using a 3-phase GFP breaker to provide the GFP requirements for circuits at marinas would work. They were not interested in discussing it.
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