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#175880 03/13/08 06:58 PM
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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?

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250.104 (B)

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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.


Bryan P. Holland, ECO.
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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.

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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.

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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)


Bryan P. Holland, ECO.
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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.


Greg Fretwell
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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!"

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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.



Bryan P. Holland, ECO.
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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.

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