Breakers as switches

[George Stolz]

Re: Breakers as switches

A circuit breaker can be used as a switch, in your case it needs to be labelled "HID".

I don't know what "AB1" means, so I can't help you out there.

What aspect of this do you see as unsafe, gasman?

 

[rick hart]

Re: Breakers as switches

This switching duty stuff may not be around much longer. Energy codes and some AHJ's are already requiring manual overrides (switches) installed in commercial buildings for all but obvious exceptions e.g. Egress lighting, only one luminaire in the room, etc.

All states must have adopted an energy conservation code by now under federal law. Most have gone with the International Energy Conservation Code. The section that references this situation in the 2003 edition IECC is 805.2.1.

Can't wait for that code forum to get up and running

 

[templdl]

Re: Breakers as switches

Molded Case Circuit Breakers and Molded Case Switches
Document Number: NEMA AB1-2002
National Electrical Manufacturers Association
01-Jan-2002
Description:
Covers molded-case circuit breakers, molded case switches, circuit-breaker enclosures, and accessory high-fault protectors.
I keep a copy of AB3 and AB4 but don't have a copy of AB1

 

[gasman]

Re: Breakers as switches

The safety issue I have is a 30,000 gallon bomb that exists in our gas tanks that is volatile. Every day I have venting that occurs sometimes at 75 feet and other times at ground level. So safety is of paramount concern at my company.

The problem I see is the misuse of breakers as my only line of defense in case of a short. If a breaker fails, all this discussion is moot and I don't know that it has failed nor do I know of a short. Every day I have people drive off with our fuel nozzles dangling from their tanks clanking down the road. I fear that one day some nitwit will cause something similar to happen to some other system.

We deal with the public day in and day out. It is my responsibility to mitigate any safety concerns should this be an area of liability. I have looked at our breakers and see no markings that make them special for HID use as a switch. Again I stress that this is my safety net from a short. I cannot say that such an event would happen but with 30,000 gallons of volatile fuel I think that a contractor for a couple of hours to install a $25 timer is cheap insurance that mitigates the liability entirely.

I am battling the forces of cheapness however as my company refuses to spend this kind of money so I have to justify it with good arguments.

 

[charlie]

Re: Breakers as switches

The safety issue I have is a 30,000 gallon bomb that exists in our gas tanks that is volatile.

I would like Bob Alexander to comment on the statement I am making here.

I believe you are being overly melodramatic with your bomb statement. The reality is that you could have a blowtorch inside the gasoline tank and the flame would go out unless you brought in oxygen in some form to allow the right mixture to ignite. Even then, there would probably not be enough to sustain a large blast.

 

[jim dungar]

Re: Breakers as switches

Not all breakers are HID rated. Those that are should have life expectancies the same as any "light switch". Those not rated should not be used as "light switches".

The most common (but not the only) mode for breaker failure is the inability to be reset due to lack of use or from overuse. Very few breakers fail to open because of too much use.

 

[gasman]

Re: Breakers as switches

Charlie,

I do not wish to elaborate on this topic only to say that 2 months ago people were saying the same kinds of things you just did and 14 souls lost their lives at a refinery. You are very wrong about the explosive nature of fuels. Additionally my background is in chemistry and rocket fuel dynamics. Safety is paramount in this area. 62000000000 billion electrons per amp per second working in a dynamic manner instantaneously moved at the speed of light, without a safety device, in a hazardous and harmonic condition, up everything goes. Two months ago that is exactly what happened. Apollo 13 comes to mind as well.

I only want a candid answer in regards to this situation. My maintenance guy came around and agreed that this needs attention and also agreed that data is the most persuasive answer. I thank all who have given me a clear picture of what this is. I will submit the data to the appropriate people and will notify them that either change the breakers or change the system.

Cheers,

Chris

 

[hardworkingstiff]

Re: Breakers as switches

gasman,

I don't understand what it is you are concerned about. Are you wanting to kill the power to the lights? The NEC does not consider the lighting in the parking lot outside of the classified location as a source of ignition. If you are concerned about the customer driving off with the nozzle, then 2 things should already be in place that should help. 1st, you should have an emergency stop button within reach of the attendant. 2nd, your hose should have a breakaway in line that will actually separate under the drive off you described, and it is designed to contain the product on both sides of the break.

Now, Charlie is correct. The air/fuel mixture in a gas tank is usually too rich to support combustion (although I wouldn't want to try the blow torch thing ).

You know those movies that show a car running over a gas dispenser and the whole station blowing up? That is melodrama.

 

[tony_psuee]

Re: Breakers as switches

gasman,

If you are venting that much fuel vapor that you still have a combustible fuel to air ratio at the height of your parking lighting, IMO using a breaker as a switch is the least of your problems. If safety is paramount, then I would like to think that you and your company are familiar with NEC Article 500 and NFPA 30A, Code for Motor Fuel Dispensing Facilities and Repair Garages. Those would be the minimum standards required for a safe facility. Cost effective is not an evil word in design and maintenance. IMO, cheap=dangerous.

Tony

 

[don_resqcapt19]

Re: Breakers as switches

For an example of the type of fire that should be expected if there is ignition of gasoline vapors at a vent, look at this video. The clip takes about a minute to load on DSL and all of the action is in the last part of the vedio.
Note that only the vapor cloud ignites and burns...the fire does not travel into the tank an explode as seen on most TV shows.
Don