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.)


"Jeff Wisnia" wrote in message
et...
Smarty wrote:
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

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

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.