Section 250.52(A)(1) 5-foot distance.

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friebel

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Pennsville, N.J.
The sentence in the Section 250.52(A)(1)states that the interior metal water piping located more than 1.52 m (5 ft) from the point of entrance to the building shall not be used as a part of the grounding electrode system or as a conductor to interconnect electrodes that are part of the grounding electrode system.
Exception: The exception reads that it is allowed in industrial and commercial buildings or structures where conditions of maintenance and supervision ensure that only qualified persons service the installation.
My question is as follows:
What is the reason that the interior metal water piping cannot be more than 5 feet from the point of entrance, but it is ok in a place that has qualified persons that service the installation.
 
Re: Section 250.52(A)(1) 5-foot distance.

It used to be that you could place the ground connection on the closest cold water pipe to the service panel. However the code changed a few years ago due to a number of cases where metallic plumbing was replaced with PVC, thus loosing the ground connection..................unless you had a supplementary ground such as a ground rod. By placing the connection within 5 feet of the street side of the meter reduces the chance of loosing your grounding electrode connection if PVC is ever installed. Also, there is current flowing (usually) on this connection since it is a parallel path with the utility service neutral. If someone broke that path by replacing a pipe without making a bonding jumper, it would be a shocking experience.
 
Re: Section 250.52(A)(1) 5-foot distance.

If someone broke that path by replacing a pipe without making a bonding jumper, it would be a shocking experience.
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Only if the grounded conductor has a high resistance or is open. If the grounded conductor is in good condition the only voltage between an "open" or broken part of the water pipe would be equal to the voltage drop on the grounded conductor. In almost all cases this the level of this voltage will be too low to cause any problems.
Don
 
Re: Section 250.52(A)(1) 5-foot distance.

The water piping system has always been considered the best point to do the grounding of the electrical system. Until the advent of plastic piping, it was no big deal. As was posted before, plastic pipe has been cut into the water piping system which rendered it useless. That is why the supplemental electrode was made mandatory but the water pipe is still the best. Therefore, if the requirement is to connect within five feet of where it enters the building, there is a better chance of the water pipe ground to remain.

In an industrial setting, the electricians generally know what is going on with their system and would not allow plastic pipe to come between the point of connection and the entry into the building. If it did happen, someone would be likely to notice it and make a change. That is why it must be exposed. :D
 
Re: Section 250.52(A)(1) 5-foot distance.

Originally posted by stud696981:
By placing the connection within 5 feet of the street side of the meter reduces the chance of loosing your grounding electrode connection if PVC is ever installed
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There is no requirement for a connection to be on the street side of the water meter that I am aware of.
 
Re: Section 250.52(A)(1) 5-foot distance.

Originally posted by electricmanscott:
There is no requirement for a connection to be on the street side of the water meter that I am aware of.
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True enough but we are required to put a bonding jumper around the meter.
 
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