ECN Forum Forums General Topics of the Trade General Discussion Area 150 A Service

Originally posted by Redsy:
Does anyone (besides me) install 150 Amp services? On a small home with gas appliances and a 60 Amp service, which needs an upgrade for central air, the load calculations still fall shy of even the minimum 100 amp mandated by code. I won't install only 100, but 200 seems excessive for such small homes. Some people feel that the materials dont cost much more for 200 than 150, so install 200. Others feel differently. Anyone?

Originally posted by resqcapt19:
[b]<I say that if you drive two rods 6' apart outside and bond to them, you don't have to
count the water main as an electrode requiring #4 copper. Indoor plumbing must be bonded, e.g., metal pipes, tanks, control boxes, and pumps.>

DS
Ground rods are considered supplemental, because of the fact that we are losing our waterline. In my area all new installations of water service is plastic and interior water piping systems have to be bonded. Also if there is a well on the premises,I live in a very rural area and there are plenty of wells, we drive two ground rods and bond to any interior water lines and jumper any that have plastic pipe inserted between them. In the county just south of me, they are required to bond to the well head and drive two ground rods. Everything is local I guess.
The interior metal water piping system must be bonded with a conductor sized per Table 250-66. See 250-104(a)(1)
Don[/B]

Originally posted by resqcapt19:
DS

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I simply assume that I need two ground rods for my primary (permanent) electrode system.

Even if you use the water pipe 2 ground rods are requires unless you can prove that a single rod complies with the 25 ohm rule in 250-56

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I don't count it as a primary electrode for a number of reasons.

At this time the code does. There are a number of reasons not to use the metal underground water piping system as a grounding electrode, but CMP5 has not yet agreed with those reasons.

The comments by Mr.Schiff about not using the metal underground piping as an electrode to improve safety of water department workers are not correct. If we stopped using it as the grounding electrode, but still bonded it to the grounding system inside the building the same safety problem will exist. The only way to improve safety for the water department workers would be to use a dielectric fitting in the water service to isolate the interior and exterior parts of the metal piping system. This is often done by gas utilities that are still using metal pipe for exterior gas supply lines.
Don(resqcapt19)