Grounding straps on water meters

[HorneTD]

Paul et. al. That simply is not true. The US National Electric Code requires that underground metal water piping that is ten or more feet in length must be used a grounding electrode. It also requires that the any interior metal water piping be bonded to the grounded conductor of the electrical service.

"250.50 Grounding Electrode System. If available on the premises at each building or structure served, each item in 250.52(A)(1) through (A)(6) shall be bonded together to form the grounding electrode system. Where none of these electrodes are available, one or more of the electrodes specified in 250.52(A)(4) through (A)(7) shall be installed and used.

250.52 Grounding Electrodes. (A) Electrodes Permitted for Grounding. (1) Metal Underground Water Pipe. A metal underground water pipe in direct contact with the earth for 3.0 m (10 ft) or more (including any metal well casing effectively bonded to the pipe) and electrically continuous (or made electrically continuous by bonding around insulating joints or insulating pipe) to the points of connection of the grounding electrode conductor and the bonding conductors. 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." Copyright 2002 National Fire Protection Association

-- Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous for general use." Thomas Alva Edison

[Jeff Wisnia]

Deja vu all over again!

That just reminded me that about 35 years ago while I was CE at Scully, I came up with an inexpensive portable water detector to measure the depth of the "water bottom" present in most gas station storage tanks and other large petroleum product tanks. It was much easier to use than smearing "water paste" on a stick and putting it in the tank long enough for the water to make it change color.

It was just a weighted bob on a wire with a coaxial conductivity probe at the bottom end and a simple battery powered circuit which produced a tone from a piezo speaker when the probe was in water. It didn't even have a power switch, as there was no battery current drain when the probe wasn't in water.

Remebering it now I just had to check, and by gosh they're still making and selling the damn things:

Jeff

[Red Cloud®]

W_Tom is a long time, and well documented usenet freak troll. His bag is to post lengthy diatribes that contain enough true technical facts to sound legit, but then he goes over the edge and adds fantasy crap. Don't ever trust ANYTHING he posts. He's got a history of this that goes back for years. He's a very clever troll, but he's nonetheless a TROLL. He has posted advice that could easily KILL somebody. That's how he gets his jollys.

rusty redcloud

[Bert Byfield]

I learned this lesson some years ago when my cousin and I were about ten years old, and he urinated on an electric fence, thinking "water" didn't conduct electricity. Impure water conducts electricity shockingly well.

[Stormin Mormon]

What did your company do about it, when there was too much water? Some kind of pump that draws off the bottom of the tank?

[Jeff Wisnia]

That was outside of our company's activities, we just made and sold a lot of differnt kinds of small equipment for use by various sections of the petroleum storage and distribution industries.

The product which got the company started back in the 1930s, and is probably the one most familiar to folks with inquiring minds anywhere that fuel oil is used for home heating, was the "Ventalarm" whistling tank fill signal. A simple gadget that during a "fill" makes a whistle sound come out of the tank's vent pipe until the oil in the tank is a few inches below "full". When the oil truck driver hears that whistle stop, he knows its time to stop filling pronto or he'll have oil spraying out the vent pipe.

To answer your question... Yes, when the water level gets too high in a gas station's tank they drop a pipe down the "stick hole" all the way to the bottom and suck out the water. Usually that is done by a service company, not the gas station personnel themselves.

The suction lines for the "gas pumps" don't go down all the way to the bottom of the storage tanks, so a fair amount of water can sit down there without screwing up your ride.

Home fuel oil tanks are subject to the same "water bottom" condition, which can cause an oil burner flameout just when you need heat the most.

I designed a floating fuel oil pickup combined with a tank level gage for those home tanks. The fuel oil gets drawn from about one inch below the surface, keeping it clear of the water and sludge on the tank bottom for as long as possible. I wanted to name it "The Scully Topsucker", but the boss wouldn't hear of it so we called it "The Snorkel". They're still making that one too.

I never did satisfy the first SWMBO's hopes that I'd someday make the cover of TIME magazine. But just for laffs, I kept this trade journal magazine cover showing "My Topsucker" and me:

Jeff

- Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."

[Bud--]

In the 2005 NEC this is 250.53. This is a "supplemental electrode". The water pipe is a great ground and is the grounding electode. The problem is it could be replaced by plastic in the future. Supplementary electrodes are protection against that possibility. Ground rod(s), which are commonly used as the supplemental ground, are not particularly good grounds. (A 25 ohm ground resistance is pretty funny.)

I have no idea what "removing electricity from the pipe" means.

Bud-- Master electrician

[GentleBen]

Bob,

There is a length of copper pipe between the plastic supply pipe and the meter. It is about a foot long and holds the shutoff valve. There also is a length of copper pipe from the meter to the connection with the internal PEX. It is about 3 ft long and has a tap on it.