Dielectric union / coupling at gas meter


Is it necessary or desirable to use a dielectric union or coupling when connecting new gas lines to a gas meter? I have seen this done in some installations but not others.
What is the correct thing to do?
Thanks for any replies / assistance.
Smarty
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Smarty wrote:

It depends upon whether your gas utility uses metal supply lines with "active cathodic protection" or not.
If they do, then they apply a low voltage to their pipes to prevent electrolytic corrosion and the dielectric unions are needed to avoid shorting that voltage to ground through the home's plumbing and/or electrical grounding system.
Best to check with your gas utility and do what they say. AFAIK nonmetalic supply lines are the defacto stardard for new installations nowadays.
HTH,
Jeff
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Jeffry Wisnia
(W1BSV + Brass Rat \'57 EE)
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In most cases an insulating coupling is part of the meter set supplied by the utility, of course, this may vary in some localities.

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Thanks also for your reply, EXT.

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Thanks Jeff (and 73's) - I was unaware that the utilities used an active method to fight electrolytic erosion / transfer. This is a retrofit to an existing meter and a 50+ year old underground supply line, so I think it best I put the dielectric union in "just in case".
Thanks again,
Smarty (another older, retired E.E.)

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Smarty wrote:

The tecnical term for that is "Impressed Current Cathodic Protection". There's a little about it here:
http://en.wikipedia.org/wiki/Cathodic_protection
73s,
Jeff
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Jeffry Wisnia
(W1BSV + Brass Rat \'57 EE)
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Good info I was unaware of. Thanks again!
Smarty

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