fuel pumps

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hounddog05

Member
Location
Ohio
I am installing some new diesel and gas fuel pumps. They are fed with a 120vac ckt. I want to use switched neutral shunt-trip breakers activated with an e-stop. cannot find the breakers in single pole, only double pole. can I install the double pole breakers and just use the one leg, or am I violating code. having trouble finding it in the code book. Thanks
 

cpinetree

Senior Member
Location
SW Florida
Are you sure they are 2 pole breakers and not single pole breakers that take 2 spaces? When you add a shunt trip it will be 3 spaces.
What kind of panel are the breakers going into?

From: http://www.schneider-electric.com.mx/documents/local/qo.pdf ->
QO-SWN and QOB-SWN Switch Neutral Circuit Breakers
The QO-SWN and QOB-SWN switch neutral circuit breakers are designed to protect gas pump
assemblies.These circuit breakers have provisions for switching the grounded conductor as outlined in
the National Electrical Code.
The QO-SWN and QOB-SWN circuit breakers are designed to simultaneously open all grounded and
ungrounded conductors. All branch circuit wiring is terminated on the load side of the circuit breaker.
The panel neutral connection is made using the pigtail lead built into the circuit breaker. Two-wire
circuit breakers require two pole spaces
; three-wire circuit breaker require three pole spaces.
QO-SWN and QOB-SWN circuit breakers are available with the complete range of QO accessories
 

hounddog05

Member
Location
Ohio
they are 2 pole breakers that take up 3 spaces. 2 for ungrounded conductors and one for the grounded conductor. Just wondering if theres anything in the code that prevents me from just using one pole on the two pole breaker.
 

kwired

Electron manager
Location
NE Nebraska
For disconnecting means purposes you must open the grounded conductor for the hazardous location (switched neutral breakers is one option for doing this) and it must be done for each individual circuit.

I think the E- Stop is part of other codes for fuel handling equipment, but do not know if it has to disconnect the grounded conductor. If it doesn't it may be possible and likely cost much less then multiple switch neutral plus shunt trip - if that is even available - then to use a shunt trip feeder breaker and feed a fuel panel and install all your switched neutral breakers in that panel. E-stop kills the entire fuel panel.

just a suggestion and needs further investigation as to whether the E stop must open the grounded conductor as well.

Back when I was doing several gas stations we were never required to put in the E-stops. But most of them have had them added since then - I just wasn't involved, and the only ones I am seeing with them added are the ones that have 24 hour fueling abilities with no attendant present.
 

hounddog05

Member
Location
Ohio
this is an unattended site, thus the need for the estop and didn't want to kill the entire panel because theres gonna be cctv and lighting, etc on it. but the pumps are just 120VAC and I don't need 2 pole breakers. But that's all they make in a switched neutral, shunt trip format. Is it against code to just use one pole on a 2 pole breaker and leave the second pole blank?
 

cpinetree

Senior Member
Location
SW Florida
If the breaker is a QO230SWN1021 I'm pretty sure that it is a single pole 120v breaker and not a double pole 120/240v breaker.
The breaker just takes a double pole space, (actually 3 spaces with the shunt trip) the switched neutral pole does not connect to the buss bar in any way.

If you have the breaker you could ohm check the other pole and verify that, I do not have one in the shop, or I would do it just to satisfy my curiosity.
Here is an ebay listing: http://www.ebay.com/itm/QO220SWN1021-NEW-IN-BOX-Square-D-Circuit-Breaker-Free-UPS-Ground-/261655989380?pt=BI_Circuit_Breakers_Transformers&hash=item3cebe98c84 it seems to be printed right on the label 120v.

Edit: added note about shunt trip taking an additional space.
 
Last edited:

kwired

Electron manager
Location
NE Nebraska
this is an unattended site, thus the need for the estop and didn't want to kill the entire panel because theres gonna be cctv and lighting, etc on it. but the pumps are just 120VAC and I don't need 2 pole breakers. But that's all they make in a switched neutral, shunt trip format. Is it against code to just use one pole on a 2 pole breaker and leave the second pole blank?
NO. In some special circumstances you may have to use both poles, but that is because of design of the breaker not codes. This would be some specialty unit though that maybe senses phase loss or something like that - not a general use inverse time breaker.

If the breaker is a QO230SWN1021 I'm pretty sure that it is a single pole 120v breaker and not a double pole 120/240v breaker.
The breaker just takes a double pole space, (actually 3 spaces with the shunt trip) the switched neutral pole does not connect to the buss bar in any way.

If you have the breaker you could ohm check the other pole and verify that, I do not have one in the shop, or I would do it just to satisfy my curiosity.
Here is an ebay listing: http://www.ebay.com/itm/QO220SWN102...uit_Breakers_Transformers&hash=item3cebe98c84 it seems to be printed right on the label 120v.

Edit: added note about shunt trip taking an additional space.

I agree - especially with info on the QO series. Though it has been a while, I have installed many single pole SWN breakers. Connects to one pole of the ungrounded bus, but the SWN feature and/or shunt trip feature for QO series each utilize the space of another pole in the panelboard. Do not know if you can get both SWN and shunt trip in a single unit or not, do know such options start to get pricey though, and also would burn up three spaces in the panel per single pole circuit if they are available - all that must be considered as well.
 

hounddog05

Member
Location
Ohio
oh ok I see what you all are saying now...I don't have the breaker in hand yet and have never installed one. Your saying that the QO230SWN1021 is a 2 pole, but only one of the poles is connected to the ungrounded bus and the other is for the grounded conductor. I was told that the 1021 in the part number refers to the shunt trip feature...is the shunt trip mechanism the reason for three spaces? ill check out the ebay link
 
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