5

I am confused about the house's main water supply grounding wires and the purpose. From here I read the following:

A jumper ground wire at the water meter is am important safety device that should be installed on most homes that have a buried copper or galvanized water supply line that brings water into the house. Buried metal water pipe makes a good ground for the electrical system and is commonly used for grounding the homes electrical system.

In most older homes the electrical systems are grounded from the electrical panel to the water supply line where it enters the house. This grounds the home’s water pipes throughout the house and is a good and safe practice that has been done for over a century. The grounding system in a home provides an easy path for electricity to flow to earth should a problem, such as a short circuit, occur.

Ok, so I get the reason to ground the electrical system to the water supply's copper pipe, but why is there a second black wire that jumps the meter?

Also, what happens if a large leak from the water valve were to short the ground wire? I'm not that knowledgeable about electrical stuff...

Enter image description here

Peter Mortensen
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blue_ego
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3 Answers3

18

The jumper is there because the meter assembly is removable. It can't be relied on for continuity and if it is ever removed for repair or replacement, you don't break the ground connection.

Even with the meter in place, if there ever was a situation where there was current on the piping system, you want it to be able to take that nice thick copper jumper path of least resistance rather than relying on the meter.

ThisOneGoesToEleven
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10

From the photo, it looks like the ground wire goes to the left side of the meter, then loops across to the right side. This provides the jumper as required.

The jumper is to prevent nasty surprises if someone removes the meter for maintenance.

The amount of current going through the ground wire should be very small. But that doesn't mean it really is very small. Installations can have current leaking to ground that nobody notices for years.

An underground metal water pipe acts as a very effective grounding rod, and fault currents can leak to Earth through it. Those currents could be coming from the breaker panel, connected to the inlet side of the meter. Or perhaps from a faulty water heater connected to the house side of the meter.

That jumper means that there can never be any significant voltage between the two sides of the meter wherever a fault lies.

Simon B
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5

Even if the main electrical ground connection is on the street side of the meter, it's not unusual for appliances (such as a dishwasher or washing machine) to have ground wires running to the nearest cold water pipe, placing them on the non-street side of the meter. So a "jumper" wire should generally be installed across the meter, to assure that the non-steet-side ground connections are connected, even if the meter's removed or loose fittings on the meter cause the pipe-to-pipe connection to fail.

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