Dielectric union / coupling at gas meter

[Smarty]

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

[Jeff Wisnia]

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

[EXT]

[Smarty]

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.)

[Smarty]

Thanks also for your reply, EXT.

[Jeff Wisnia]

The tecnical term for that is "Impressed Current Cathodic Protection". There's a little about it here:

73s,

Jeff

[Smarty]

Good info I was unaware of. Thanks again!

Smarty