Can anyone direct me to the NEC article that spells out grounding requirements for butane gas tanks? These tanks will be located outdoors and are used as a foaming agent in our industrial manufacturing process. There are no electrical devices on the tanks themselves. However there are some 480v disconnects that serve other equipment in the area. I believe the location of this equipment are classified as Class I, Division 2. Also, I was asked to ground these 1000 gallon tanks (there are two of them) for static electric potential. Any guidance will greatly be appreciated.
Grounding a butane gas tank.
- Thread starter curd
- Start date
- Status
Re: Grounding a butane gas tank.
Yes, there is a code compliant grounding electrode system within 50ft of these tanks. There is a genearal opinion that an isolated grounding electrode not connected to the system is sufficient, particularly where it relates to static buildup. Static discharge is a major component in the plastics industry. Should this not be bonded to the GES?
Yes, there is a code compliant grounding electrode system within 50ft of these tanks. There is a genearal opinion that an isolated grounding electrode not connected to the system is sufficient, particularly where it relates to static buildup. Static discharge is a major component in the plastics industry. Should this not be bonded to the GES?
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
Re: Grounding a butane gas tank.
The NEC doesn't speak to this directly. The appropriate Standard is NFPA 54, The National Fuel Gas Code.
Grounding/bonding requirements are largely dependent on the fuel delivery methods, inherent bonding and the likelihood of non-electrical equipment becoming energized.
[Edit Add;] An isolated grounding electrode would probably be useless and potentially dangerous depending on the "geometry" of the overall installation.
[ September 23, 2004, 05:23 PM: Message edited by: rbalex ]
The NEC doesn't speak to this directly. The appropriate Standard is NFPA 54, The National Fuel Gas Code.
Grounding/bonding requirements are largely dependent on the fuel delivery methods, inherent bonding and the likelihood of non-electrical equipment becoming energized.
[Edit Add;] An isolated grounding electrode would probably be useless and potentially dangerous depending on the "geometry" of the overall installation.
[ September 23, 2004, 05:23 PM: Message edited by: rbalex ]
Re: Grounding a butane gas tank.
Because of a general lack of knowledge about grounding and bonding techniques in my plant, it is assumed anything tied to a ground rod is made safe as long as it is driven 8ft into the earth. Fires are not at all rare here, mainly because of the gas that is used to make foam. Static buildup is an inherent characteristic in this process. Where can I find more info about this NFPA 54? Can it only be purchased? We use antistat bars in some installations such as foam roll winders which act as huge capacitors. I also would like to mention that on several installations I measure current (up to 2 amps) on the equipment grounding conductors.
Because of a general lack of knowledge about grounding and bonding techniques in my plant, it is assumed anything tied to a ground rod is made safe as long as it is driven 8ft into the earth. Fires are not at all rare here, mainly because of the gas that is used to make foam. Static buildup is an inherent characteristic in this process. Where can I find more info about this NFPA 54? Can it only be purchased? We use antistat bars in some installations such as foam roll winders which act as huge capacitors. I also would like to mention that on several installations I measure current (up to 2 amps) on the equipment grounding conductors.
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
Re: Grounding a butane gas tank.
The standard may be purchased and downloaded from NFPA's website.
Its less than $40.
If you are measuring 2A on your EGCs you have some serious problems that I wouldn't even speculate about. You need a professional evaluation.
The standard may be purchased and downloaded from NFPA's website.
Its less than $40.
If you are measuring 2A on your EGCs you have some serious problems that I wouldn't even speculate about. You need a professional evaluation.
Re: Grounding a butane gas tank.
Your installtion is not a NEC issue, as Robert indicated NFPA 54, which I am not familar with.
However I am sure all ground electrode systems would be required to be bonded. Therefore I would think your tank should be bonded to the GES via a #6 AWG copper conductor.
Are you implying you have independant ground electrode systems, that are not bonded together? That is asking for trouble.
Your installtion is not a NEC issue, as Robert indicated NFPA 54, which I am not familar with.
However I am sure all ground electrode systems would be required to be bonded. Therefore I would think your tank should be bonded to the GES via a #6 AWG copper conductor.
Re: Grounding a butane gas tank.
Replied by dereckbc
However I am sure all ground electrode systems would be required to be bonded. Therefore I would think your tank should be bonded to the GES via a #6 AWG copper conductor.
So, since the water piping system and the building steel are grounded according to NEC requirements, is it acceptable to bond the tanks to a nearby steel column?
Replied by dereckbc
However I am sure all ground electrode systems would be required to be bonded. Therefore I would think your tank should be bonded to the GES via a #6 AWG copper conductor.
So, since the water piping system and the building steel are grounded according to NEC requirements, is it acceptable to bond the tanks to a nearby steel column?
Re: Grounding a butane gas tank.
There are a couple points I would like to make.
1. A ground rod may be the worst of all choices for a grounding electrode. If it is in dry sand, it will not be of low enough impedance to do any good. 2. Two separate grounds may have a difference of potential between them. One is at a good earth ground and the other is not. 3. There should be no current on a grounding system. It is there to trip the overcurrent device and/or limit potential on the wiring if there is a fault. 4. OSHA requires all fuel storage vessels to be grounded. (OSHA CFR 1910.110).
Those butane tanks must be grounded to a good ground which should be to the plants ground electrode system which, if installed correctly, is bonded to the building steel. The column (if bonded) is an excellent ground for the tanks.
Butane will vaporize at 30 degrees at atmosphere pressure. Any leak and any spark will cause an explosion.
I work at a propane processing plant. There are no columns more than 40 ft from a ground rod (3/4 X 10). There is not an inch of conduit without a grounding conductor. Every motor has an additional external ground. Every section of cable tray is bonded. All external equipment grounds are 2/0 or larger even to the ground rods. The whole plant is Class 1 Division 2. We have over a million gallons of propane. I cannot over emphasize the importance of the grounding system.
[ September 25, 2004, 08:59 PM: Message edited by: derwith ]
There are a couple points I would like to make.
1. A ground rod may be the worst of all choices for a grounding electrode. If it is in dry sand, it will not be of low enough impedance to do any good. 2. Two separate grounds may have a difference of potential between them. One is at a good earth ground and the other is not. 3. There should be no current on a grounding system. It is there to trip the overcurrent device and/or limit potential on the wiring if there is a fault. 4. OSHA requires all fuel storage vessels to be grounded. (OSHA CFR 1910.110).
Those butane tanks must be grounded to a good ground which should be to the plants ground electrode system which, if installed correctly, is bonded to the building steel. The column (if bonded) is an excellent ground for the tanks.
Butane will vaporize at 30 degrees at atmosphere pressure. Any leak and any spark will cause an explosion.
I work at a propane processing plant. There are no columns more than 40 ft from a ground rod (3/4 X 10). There is not an inch of conduit without a grounding conductor. Every motor has an additional external ground. Every section of cable tray is bonded. All external equipment grounds are 2/0 or larger even to the ground rods. The whole plant is Class 1 Division 2. We have over a million gallons of propane. I cannot over emphasize the importance of the grounding system.
[ September 25, 2004, 08:59 PM: Message edited by: derwith ]
- Location
- Illinois
- Occupation
- retired electrician
Re: Grounding a butane gas tank.
derwith,
Don
derwith,
Can you expand on this? The grounding electrode system has almost nothing to do with fault clearing and really does little to limit the potential under fault conditions.
Don
izak
Senior Member
- Location
- Springfield, MO
Re: Grounding a butane gas tank.
yes i am curious about this as well...
I am having trouble understanding how a grounding electrode can have anything to do with clearing a fault...
my current instructor says that a ground rod (or other electrode) serves only for lightning protection.
but i am also hearing from other people that he is totally wrong.
can anyone speak intelligently on this subject?
yes i am curious about this as well...
I am having trouble understanding how a grounding electrode can have anything to do with clearing a fault...
my current instructor says that a ground rod (or other electrode) serves only for lightning protection.
but i am also hearing from other people that he is totally wrong.
can anyone speak intelligently on this subject?
Re: Grounding a butane gas tank.
I said the grounding system. You guys are talking about the grounding electrode. A fault such as an ungrounded conductor shorted to ground. It trips the overcurrent protecting device. A fault such as lightning. It is directed to the grounding system. We can have two sources of power. The generated power we are connected to, and lightning. The grounding system must address both. Can anybody speak intelligently about this?
I said the grounding system. You guys are talking about the grounding electrode. A fault such as an ungrounded conductor shorted to ground. It trips the overcurrent protecting device. A fault such as lightning. It is directed to the grounding system. We can have two sources of power. The generated power we are connected to, and lightning. The grounding system must address both. Can anybody speak intelligently about this?
- Location
- Massachusetts
Re: Grounding a butane gas tank.
250.4(A)(5) prevents us from using the grounding electrodes as the effective ground-fault current path.
You did?
It looks very much like you are saying a low impedance grounding electrode will clear faults.
250.4(A)(5) prevents us from using the grounding electrodes as the effective ground-fault current path.
- Location
- Massachusetts
Re: Grounding a butane gas tank.
For instance say a high voltage line lands on the bare neutral of an overhead service.
IMO that is pretty much it, take a look at 250.4(A)(5). The electrodes might also be of some service if high voltage from the power company gets onto the customers wiring.
For instance say a high voltage line lands on the bare neutral of an overhead service.
- Location
- Illinois
- Occupation
- retired electrician
Re: Grounding a butane gas tank.
These posts are a perfect example of why the term grounding needs to be reserved for connections to the earth. Most of what we now call grounding is really bonding and the code needs to be changed to reflect this fact.
Don
These posts are a perfect example of why the term grounding needs to be reserved for connections to the earth. Most of what we now call grounding is really bonding and the code needs to be changed to reflect this fact.
Don
- Location
- Illinois
- Occupation
- retired electrician
Re: Grounding a butane gas tank.
Don
If it clears the fault, it is not shorted to "ground". It is shorted back to the source.
Don
- Status