Gounding of Flammable Cabinets

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BTippy

Member
Location
Gainesville, Ga
I have several Flammable cabinets that have a grounding connection. These cabinets refer to NFPA Code 30 as being the code to regulate the construction. NFPA Code 30 doesn't talk about grounding. Would these cabinets be regulated by NEC regulations? If so, which one?

Any help that you could give would be greatly appreciated!

Thanks in advance for any and all help!
 

tom baker

First Chief Moderator
Staff member
250.54 Supplemental Grounding Electrodes.
This is an electrode that is not required by the NEC.
The cabinets do not fall under the scope of the NEC as they do not have "premise wiring".
 

ryan_618

Senior Member
I beleive this is actually bonding, in an effort to eliminate statice discharge. It is my understanding that the cabinets are typically bonded together with an 8 AWG conductor, but I am not positive on this.
 

james wuebker

Senior Member
Location
Iowa
ryan_618 said:
I beleive this is actually bonding, in an effort to eliminate statice discharge. It is my understanding that the cabinets are typically bonded together with an 8 AWG conductor, but I am not positive on this.

Ryan, You are correct. You can bond them together and use a Ground rod. That is what OSHA wants. I'll try to find out what section it's in and get back.
Jim
 
If you drive the ground rod it will have to be bonded to the building grounding electrode system. A supplemental grounding electrode is allowed to be bonded to the equipment ground serving the equipment.
 

rbalex

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Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
NFPA 30, Chapter 6 specifically references the NEC as the basis of electrical installations.

Within Class I Locations, Section 501.30 covers Grounding/Bonding. Class II and III have analogous Sections. Neither Supplemental nor Supplementary electrodes are required.
 

james wuebker

Senior Member
Location
Iowa
stormywyo said:
If you drive the ground rod it will have to be bonded to the building grounding electrode system. A supplemental grounding electrode is allowed to be bonded to the equipment ground serving the equipment.

I will find it soon, but NO the Ground rod for the flammable cabinet doesn't have to be bonded to the building grounding electrode system. OSHA requires this rod for the static charge that could help when let's stay pouring gas into another container at this cabinet. Which in that case you also would need a wire from the grounded cabinet to the container your pouring the gas into. I haven't located this this yet in the OSHA book but when I get it I will add to this forum.
Jim
 
And "yes" it does have to be bonded according to 250.50 since it does not qualify for a supplementary grounding electrode under 250.54. If you don't bond it as per the NEC you are creating a potential hazard.
 

james wuebker

Senior Member
Location
Iowa
stormywyo said:
And "yes" it does have to be bonded according to 250.50 since it does not qualify for a supplementary grounding electrode under 250.54. If you don't bond it as per the NEC you are creating a potential hazard.

Explain what hazard you are creating. There's no electricity at the flammable cabinet. The ground rod is there for potential static electricity. Static charge with flammable liquids can cause a fire or explosion. That is why OSHA wanted me to install a ground rod.
Jim
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
BT,
Take look at NFPA 77: Recommended Practice on Static Electricity. I think that it may cover your application.
Don
 
You are creating grounded cabinets that could be at a different potential then other metal surfaces and equipment that are bonded through the the electrical services grounding/bonding system. I guess you would need to explain to me how you are complying with the NEC cause I don't see it. I see it as the same problem that came up in the '80s with the computer and data people wanting their own separate grounding electrode system without bonding it to the building system. And what is it going to hurt to comply with the NEC?
 

iwire

Moderator
Staff member
Location
Massachusetts
stormywyo said:
I guess you would need to explain to me how you are complying with the NEC cause I don't see it.

I don't see a violation of the NEC at all.

I don't see where you get this idea.

since it does not qualify for a supplementary grounding electrode under 250.54

There is nothing to qualify, I can add a rod and call it a Supplementary grounding electrode.

250.54 Supplementary Grounding Electrodes.
Supplementary grounding electrodes shall be permitted to be connected to the equipment grounding conductors specified in 250.118 and shall not be required to comply with the electrode bonding requirements of 250.50 or 250.53(C) or the resistance requirements of 250.56, but the earth shall not be used as the sole equipment grounding conductor.

Now where is the requirement that this rod be bonded to any other electrodes?



stormywyo said:
I see it as the same problem that came up in the '80s with the computer and data people wanting their own separate grounding electrode system without bonding it to the building system.

That is not the same thing at all.

In the case of the computers they are supplied with a branch circuit that the NEC requires an EGC for that eventually must be bonded to the neutral.

The cabinets in this case have no branch circuit to require an EGC.

There is no NEC requirement for this rod at the fire cabinets to be bonded to the other building electrodes.
 
Since a definition of supplementary grounding electrode is lacking, I only am looking at the requirements of 250.54. Since there is no equipment grounding conductor available it will not fall under this definition and would be required to comply with 250.50.
 

james wuebker

Senior Member
Location
Iowa
stormywyo said:
Since a definition of supplementary grounding electrode is lacking, I only am looking at the requirements of 250.54. Since there is no equipment grounding conductor available it will not fall under this definition and would be required to comply with 250.50.
This system (Flammable Cabinet)has nothing to do with any type of a electrcial system. This is for static charge if the cabinet should ever create it. If you have work in an industrial plant were there are barrels of flammable equipment then you know about static charge that could happen to the flammable barrels causing fires or explosions. There's no electricity in this setting. It's just like if you were out on a farm and the farmer had a barrel of gas(500 gallons) for his tractors or some other machinery. No electric pump just open the valve and gas would fill up the tank. There is always a chance of static electricity there but if you would install a ground rod there and bond it to the barrel you would have a lot better chance and it would help do away of a static charge which then there would be less chance of a fire or explosion happening while filling up his tractor. Hope you can understand where I'm coming from.
Jim
 

iwire

Moderator
Staff member
Location
Massachusetts
First welcome to the Forum Stomy, I hope you stick around. :)

stormywyo said:
Since a definition of supplementary grounding electrode is lacking,

The 'definition' of a supplementary grounding electrode is simply any electrode that is not required by the NEC.

Since the NEC does not require an electrode at this cabinet any electrode connected to it would be a supplementary grounding electrode.

It really is that simple.

There is no danger in not bonding this cabinet to the rest of the electrical system as the cabinet is not supplied by a feeder or branch circuit.

It is not 'likely to become energized' any more than a file cabinet in an office building is likely to become energized.

By the way, 250.54 permits supplementary grounding electrodes to be connected to the EGC, it does not require it to be done or require that an EGC is available.

Again this is an entirely different situation than replacing an EGC to a computer with just a rod. I agree with you that is a dangerous NEC violation.

Bob
 

BTippy

Member
Location
Gainesville, Ga
I think what I read here tells me that the grounding of these cabinets doesn't fall under NEC but would fall under OSHA and NFPA regulations. Both myself and the local fire chief have gone over the NFPA and local regulations and we couldn't find any specific reference to grounding of storage cabinets other than "sufficient grounding" and I believe that the OSHA requirements are that when dispensing fluids from these cabinets both the cabinet and the receiving container both need to be grounded.

Thanks for all the information, guys! I really look forward to learning more by reading through the posts on this forum!


Butch
 

hornetd

Senior Member
Location
Maryland
Occupation
Journeyman Electrician, Retired
Flammable liquid cabinet bonding

Flammable liquid cabinet bonding

This is what I observed in the flammable liquid handling areas of facilities that I worked in. These cabinets have the external connection so that the cabinets can be bonded to each other and to any adjacent work surface. Metal tables are used in flammable liquid dispensing areas and they are bonded to the cabinets. The work surface is fitted with one or more bonding straps to attach to containers while filling or pouring from them.
 

BTippy

Member
Location
Gainesville, Ga
We only have the cabinets to store aerosol cans and small amounts of some other flammable fluids. We really don't do any "dispensing" of fluids at the cabinets themselves. I was just trying to cover all the bases when I grounded the cabinets. I was asked by my boss (who was told by someone that we weren't following the NEC) to find out what the NEC, OSHA and NFPA regulations require. I came up with pretty much what everyone here came up with but I just wanted to see if maybe someone else had read something that I hadn't.

Keep up the good work guys!
 
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