Originally Posted By: David Suelflow This post was automatically imported from our archived forum.
I know the plumbing should be bonded and why (thanks to some outstanding posts, Thanks guys) but why does it need to be within a few feet of the service (water) entry? If it is farther away does that pose a hazard and why?
Originally Posted By: bbadger This post was automatically imported from our archived forum.
No easy NEC answers.
If we are talking about just bonding the metal water piping system that can be done anywhere on the water piping system.
If we are talking about using the water piping as a grounding electrode then that connection must be within 5' of the entrance.
I will try to give some examples.
First example
A building is served by a plastic water pipe from the water company once inside the building the pipe is copper.
We can not use the water pipe as a grounding electrode because the underground section is plastic.
In this case all we will do is bond the interior metal piping at any location, this ensures the interior metal piping is not energized by a faulty piece of equipment like an electric water heater or any number of other appliances etc.
Second example
A building is served by a metal water pipe from the water company once inside the building the pipe is plastic.
In this case the underground water pipe qualifies as a grounding electrode and we must run a grounding electrode conductor to it within 5' of the entrance.
Why must it be close to the entrance?
Added safety for those working on the water lines inside the house.
A water pipe used as the grounding electrode often has current flowing through it. If you separate the pipe to work on it between the street side and the point the grounding electrode conductor is connected you are very likely to get a shock.
This is also one of the reasons items like water meters must have bonding jumpers around them.
-- Bob Badger
Electrical Construction & Maintenance
Moderator at ECN
Originally Posted By: roconnor This post was automatically imported from our archived forum.
For an existing home I dont think the distance is really the important issue. I think it’s important that the main service bond/ground connection be made before any valves/fittings/etc. likely to be encountered beyond 5’ from the water main entrance (and are likely to be serviced/replaced).
There should also be a bonding jumper wire across/around any water meter and other items that can be removed ... like a water heater.
As Bob explained, bonding is done to ensure a breaker will trip if metal piping becomes energized/hot (as long as everything is correctly connected back to the service panel/equipment) ... and to provide protection from lightning and other voltage spikes.
Just my opinion and 2-nickels ... 
-- Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: jtedesco This post was automatically imported from our archived forum.
Quote:
250.68(B) Effective Grounding Path.
The connection of a grounding electrode conductor or bonding jumper to a grounding electrode shall be made in a manner that will ensure a permanent and effective grounding path.
Where necessary to ensure the grounding path for a metal piping system used as a grounding electrode, effective bonding shall be provided around insulated joints and around any equipment likely to be disconnected for repairs or replacement.
The reason for the bonding jumper here is so that it will be long enough so that the equipment can be removed for repair or replacement. This was added to the code to protect the water department service person.
Bonding conductors shall be of sufficient length to permit removal of such equipment while retaining the integrity of the bond.
