Fuel Dispenser Disconnect

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k0y0te

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I'm trying to make sure that I'm understanding the disconnect requirement in article 514.

If I have a pair of fuel dispensers, each fed from its own single phase circuit. Can I use a pair of three pole disconnects just outside of the 20' classified area to disconnect all three conductors?

Or does it have to be a single disconnect?

514.11(C) indicates that "Emergency controls shall shut off all power to all dispensing equipment at the station."

Is it saying that one disconnect needs to be used to de-energize both dispensers at the same time, or that the controls just need to be capable of disconnecting both dispensers (ie. two switches would be fine).

Most likely I'm reading more into this than I need to.

Thanks.
 
It's a self service fleet fueling station. So there will be times when it is in service, but unattended.
 
k0y0te said:
It's a self service fleet fueling station. So there will be times when it is in service, but unattended.
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If its unattended you need an" all stop" that shuts off all current carrying conductors to all dispensers. At least thats the way its enforced in Maine
 
NFPA 30A section 6.7 requires an emergency shutoff to disconnect all dispensing devices and all remote pumps serving the dispensing devices. You also have to disconect all associated power, controll and signal circuits and all other electrical equipment in the classified area locations surrounding the dispensing units. I believe a shunt trip is used to accomplish this...

shortcircuit2
 
08' NEC indicates that all conductors, including the ground, must be disconnected. Unless I'm missing something.

I'm not sure how you would get a shunt trip breaker to disconnect a hot, neutral, ground, and the control conductors. Unless you used the shunt trip to power the coil on a set of contactors. Then a simple push button could be used to trip the breaker and open the contacts.

Looks like the best bet is to run everything through an electrically held, normally open contactor with a push button.

Seems kinda complicated when a multi pole safety switch would accomplish the same thing.
 
k0y0te said:
08' NEC indicates that all conductors, including the ground, must be disconnected. Unless I'm missing something.

I'm not sure how you would get a shunt trip breaker to disconnect a hot, neutral, ground, and the control conductors. Unless you used the shunt trip to power the coil on a set of contactors. Then a simple push button could be used to trip the breaker and open the contacts.

Looks like the best bet is to run everything through an electrically held, normally open contactor with a push button.

Seems kinda complicated when a multi pole safety switch would accomplish the same thing.
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You don't have to switch the ground, you have to switch the grounded conductor aka the neutral. Shunt trips won't work unless its a switch neutral shunt trip? Never seen one but if its made I'll bet its expensive. I generally use open face relays, as many as it takes to switch all the neutrals and all the hots for the system. Some folks use a large 3 pole contactor to switch the sub panel running the gas. Make sure the fire suppression system isn't in that subpanel.
 
I have inspected shunt trip breakers specifically designed to open all conductors at the pumps but I have also inspected approved contactors that do the same thing.
 
I remember back in the '60s, when I was an apprentice, we hooked up some gasoline pumps. I noticed that the journeyman that I worked under intended to use the breakers in the panel as the disconnects. They were in sight but wouldn't open the neutral. After letting him know that we were supposed to break both conductors, he ran it by the shop's owner. The owner just happened to be the town inspector. He, the boss, let me know that as a lowly helper I should just butt out and do what I was told. Those pumps ended up getting installed with just the "hot" leg being disconnected and passed inpection just fine. I lost a lot of respect for my boss that day. My journeyman should have known better too.
 
LCD displays, onboard intercoms, video capabilities, point of sale card readers electrically powered at dispensing units in the classified area surrounding the dispensing unit must be disconnected simultaneously with all other power to the dispensing units...
 
shortcircuit2 said:
LCD displays, onboard intercoms, video capabilities, point of sale card readers electrically powered at dispensing units in the classified area surrounding the dispensing unit must be disconnected simultaneously with all other power to the dispensing units...
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Never seen anyone shut down intercom, LCD will go down with the pump. Card readers in the pump go down with the pump, pedestal mounted card readers may or may not be in the area. Video is usually above the area
 
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