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Posted By: watthead Ground rod for gas piping. - 03/13/08 10:58 PM
The propane man installed a ground rod connected only to ground his flex piping system and was not bonded to the structures grounding system. 250.52 tells me that he should not drive a ground rod independant of the grounding system. Am I right on this? Are there any other references?
Posted By: Yoopersup Re: Ground rod for gas piping. - 03/14/08 01:42 AM
250.104 (B)
Posted By: BPHgravity Re: Ground rod for gas piping. - 03/14/08 06:04 PM
Grounding metal gas piping serves no purpose.

I agree with Yoopersup that 250.104(B) requires the Bonding of metal gas piping if it is likely to become energized as indicated in the section.

While not directly related to your question, "auxiliary grounding electrodes" are not required to comply with most of the requirements in Article 250. See section 250.54 of the NEC.
Posted By: renosteinke Re: Ground rod for gas piping. - 03/15/08 01:26 AM
It is an interesting question ... one about which I know little.

This forum has had pictures of LPG tanks with grounding electrodes attached. I know not the reason - gas code is not one I'm familiar with - but it seems to be a common practice .... especially where there is any chance voltages will be induced by overhead lines, radio towers, etc.

It's also not impossible that the rod seen being driven was a sacrificial anode.

If it is meant for grounding, I see no harm in also tying it to the household ground net. Yet, without there actually being power at this detached tank, I'm not sure you're required to connect it.
Posted By: Check Pilot Re: Ground rod for gas piping. - 03/15/08 04:51 AM
If this means anything to you NV, which it probably won't, we here in Alberta are required to ground (earth) at the nearest point of exit of any LPG -i.e. propane - appliances, which includes propane tanks that are connected to or near a building.

The key words are "near" which could include barbeque's. We have no requirements to connect the ground (earth) as a separate electrical source in the Province's rules, - Yet, to make it doubly safe - we do drive ground rods down about 35 feet (12 meteres) and use 2/0 copper conductors within 30 (10 meters)feet away from the tank to prevent lightning strike damage to the tank. I wish, but am not hopeful for a rule to come forward to this issue, but so far here in Canada - there is none that I'm aware of.

We do not hook the grounds (earths) up to the house grounds for obvious reasons, if we can avoid it (mostly at all costs), for obvious reasons of not letting the lightning strike into the house.

Hope that helps.
Posted By: BPHgravity Re: Ground rod for gas piping. - 03/15/08 12:34 PM
Originally Posted by Check Pilot
...Yet, to make it doubly safe - we do drive ground rods down about 35 feet (12 meteres) and use 2/0 copper conductors within 30 (10 meters)feet away from the tank to prevent lightning strike damage to the tank...


This makes no sense and is a complete waste of time, material, and energy. The only way to POSSIBLY prevent damage from lightning is to install a conventional LPS in compliance with the NFPA 780. In all honesty, the installation you describe above serves no purpose.

Quote
We do not hook the grounds (earths) up to the house grounds for obvious reasons, if we can avoid it (mostly at all costs), for obvious reasons of not letting the lightning strike into the house.


Anytime you connect an object to earth at one point and then connect another object at another point, a potential will be established as ground potential rise occurs at or near the strike termination point. This difference of potential is what allows hazardous currents to flow and/or allows inductive arcing between nearby objects at these differences in potential.

BONDING of anything and everything conductive together and to the service grounding electrode system is usually your best bet.

Fancy and excessive GROUNDING techniques have never been a solution for electrical nor lightning issues. (except in extraordinary circumstances)
Posted By: gfretwell Re: Ground rod for gas piping. - 03/15/08 03:19 PM
I agree with Bryan. We did a lot of lightning mitigation in Ft Myers but it was all based on "bonding" not "grounding". We still used the single point grounding electrode concept at the service and when we found a couple separated electrodes we bonded them together.
Posted By: renosteinke Re: Ground rod for gas piping. - 03/15/08 03:42 PM
Just a friendly reminder ... different places do things differently. Different materials and methods are used. Ir's very possible that there are other 'normal' things the Canadians do that combine with what Check Pilot describes for it all to make sense.

As Vinnie Barbarino often said: "I get so confused!"
Posted By: BPHgravity Re: Ground rod for gas piping. - 03/16/08 12:24 AM
Electricty and lightning works the same way in Canada as it does in the US...

And ground rods, no matter where they are installed, serve such a limited purpose that no length, no depth, nor any size GEC attached to them will change that fact.

Posted By: renosteinke Re: Ground rod for gas piping. - 03/16/08 12:58 AM
Bryan, you 'off the hip' comment is simply, well, uninformed.

Heck, vast parts of the modern world have electrical systems that are completely without any form of GEC. Describe a ground rod to a Norwegian, and he'll tell you that's the silliest thing he's ever heard of.

Canada may be very similar to the USA, but there are enough differences between our codes that manufacturers usually have to make different equipment for the two markets.

We are also assuming we understand the reason for the rod at the tank. We don't know that ... there might be another reason. For example, few people realize that fuel - be it oil, gasoline, propane, whatever - can generate it's own static when flowing. For all we know, that rod plays a role only when the tanker is filling the tank.
Posted By: gfretwell Re: Ground rod for gas piping. - 03/16/08 04:24 AM
Quote
Describe a ground rod to a Norwegian, and he'll tell you that's the silliest thing he's ever heard of.


I bet they don't have an ass kicking thunderstorm every day for about 6 months of the year in Norway ... or Canada.

When they do I suspect they just say "there is nothing you can do about a lightning strike" and eat the blown up equipment.
Posted By: watthead Re: Ground rod for gas piping. - 03/16/08 12:04 PM
The rod was placed not at the tank but at the house where its GEC was attached to the piping. The gasman said it was to protect the flexible pipe he used from becoming perforated by lightning. He also said that if he had used only schedule 40 black pipe that he would not need the grounding electrode. Thanks for the 250.104(B) reference as I had not looked at that one. I would have told him that the NEC said all ground rods must be bonded as in 250.52. I guess it was best that I didn't offer my erronious view of the Code. Thanks for all the input.
Posted By: BPHgravity Re: Ground rod for gas piping. - 03/16/08 12:27 PM
Originally Posted by renosteinke
...We are also assuming we understand the reason for the rod at the tank. We don't know that ... there might be another reason. For example, few people realize that fuel - be it oil, gasoline, propane, whatever - can generate it's own static when flowing. For all we know, that rod plays a role only when the tanker is filling the tank.


Again, GROUNDING will do little to nothing to equalize the charge separation created between two conductive bodies by the flow of liquids. BONDING of the liquid transfer equipment on the other hand, will help reduce the potential of static discharge.

The NPFA 77 establishs a value of 10 ohms for this purpose. However, it has been well established by both the NFPA and IEEE that bonding resistance in the area of 1,000,000 ohms is sufficient to reduce static charges on equipment.


On a side note, I am aware that my comments on grounding and bonding topics are sometimes radical and fly in the face of nearly 100 years of code practices. It has been sometime since I have been active on this forum, but I do visit the forum frequently and read most of the posts. While many of the members here know me from other forums and have come to know where I stand on cetain aspects of Article 250 and the NFPA 780, others may not and assume my comments are unfounded, unsupported, or uneducated. I apologize it it appears that I am being difficult rather than helpful. That is not my intent.

If this discussion was on the topic of say, communication towers, we may have some issues of grounding to cover. But, when it comes to the topic of "ground rods for gas piping", there really is no purpoe grounding can serve.
Posted By: renosteinke Re: Ground rod for gas piping. - 03/16/08 02:03 PM
Thank you, Bryan, for your gracious reply.

I spent a fair amount of time overseas, where I quickly learned that even the simplest tasks are capable of being performed in a manner that most would never even be able to recognize. With a wee bit of patience on my part, I nearly always found that there was a method to the madness - once you had the 'big picture.'

I have no idea why the rod was driven, or what purpose was served. Add that to the LONG list of things I don't understand. I've just seen enough to support the basic premise that folks are not stupid, and there is generally a good reason behind every practice. My ignorance of that reason does not translate into the practice being silly laugh
Posted By: Check Pilot Re: Ground rod for gas piping. - 03/18/08 02:18 AM
Hi Bryan,

Sorry I haven't been able to respond until now regarding your comments.

It may seem like what we are doing is unnecessary. The reason for grounding the tanks however, is that there is usually no other way of dissipating any sudden discharge from whatever the source might be such as a really high powered FM or TV transmitter in the neighbourhood or a nearby or direct lightning strike.

We've had both the RF stuff and lightning around the tanks we've worked with and so far there has not been any issues.

The key to most of this is the codes for connections on the tanks here in Alberta. It is not allowable, to my knowledge, (unless I need some further education) in most circumstances to use any kind of metal piping and therefore, any electrical connection, from the tank and the entry point of a building for use with anything but natural gas supplied by a pipelined energy supplier. (Read the "gas company). Essentially the tank is sitting out there "on it's own" with zero protection from either RF or lightning so there is no common bonding point available.

As I said previously, we do not have a really clear rule that I can find on bonding these tanks to much of anything. I thought it would be basic to do it, and hopefully someone will be able to point me in the right direction if I'm misguided about it all here. I the meantime I think it's best to continue to try and get as tight a bond to earth as we can.
Posted By: Alan Nadon Re: Ground rod for gas piping. - 03/18/08 03:24 PM
The original message claimed that the ground rod was being installed because of the use of flexible gas piping. if it is coated stainless steel tubing (CSST) it is being done not to comply with 250.104 but as a manufacturers requirement to BOND the piping system to the building grounding syatem.
A seperate ground rod does not comply with the manufacturers requirements.
Different manufacturers have different requirements. Get the brand name and Google them and check their eng. spec. page.
Posted By: George Little Re: Ground rod for gas piping. - 03/18/08 07:48 PM
Alan- My friend, while I agree with your statement regarding the bonding, the proper description of CSST is "Corrugated Stainless Steel Tubing" albeit coated the letters do not stand for coated. I should also say that the non corrugated connecting "whips" that are used for gas stove and dryer hook-ups are not what are the issue, it is the coated stuff we are talking about. There is a wealth of information on the Michigan Chapter IAEI web site at http://www.iaei-michigan.org and when there, go to products and see what each manufacturer ask for bonding.
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