Odd electrical problem

[Limp Arbor]

So the ice storm the othe day took down many trees in our area. My BIL called me because a branch fell and knocked his neutral wire loose from the weatherhead. Some things worked others didn't, biggest problem was when the fridge kicked on the whole house went dim.

I asked him about a ground rod and he was sure he didn't have one. Until he could get a guy to climb up there I told him to go get a ground rod at the Borg and pound it in as far as he could and connect it to the ground/neutral bar in his panel. He was able to get the ground rod about 5' down with a hammer and connected two 12ga copper wires from the rod to his panel. After he did this there was no improvement at all.

An hour later an electrician he knows showed up and reconnected the neutral to the weaterhead and all was better. Neither of his hot leads at the weatherhead were loose or needed to be touched. So why wouldn't going directly to ground from the panel have helped his problem?

[dpb]

'Cuz the neutral bus that was disconnected was/is isolated.

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[bud--]

As an earthing electrode ground rods suck. A very good resistance to earth would be 10 ohms. If you connect a hot wire to the rod you get a current of 12A.

In this case the rod is 5 ft instead of 8 feet. But much worse - it is in frozen ground. Frozen ground has a much higher resistance than non-frozen ground.

I would not expect a ground rod to be very effective for an open neutral in the best case. This was not the best case.

The reason the earthing system might work at all is the N-G bond required in US services. The earthing system is not intended to be a substitute neutral.

If the electrode is a water pipe (which is required to be an earthing electrode if there is 10 ft of metal in the earth), and you have a metal municipal water system, you can have the neutral current through the earthing connection to the water service, through the metal water supply lines to adjacent houses, to the services for those houses, and back to the utility through the service neutrals in those houses.

You might want to find out how the system is earthed.

[trader4]

He may not have a seperate ground rod, but I'll bet that his panel does have a grounding conductor that connects to earth ground through another means, typically an underground cold water pipe. And if it doesn't, that needs to be fixed ASAP.

Because:

A - It was likely grounded to begin with

B - The ground isn't designed for or capable of providing the same high current capacity back to the transformer that the service neutral conductor can handle.

[HeyBub]

The purpose of attaching a ground wire to a water pipe is not to provide a ground for the electrical service, it is to provide a ground for the plumbing system.

[bud--]

The same nonsense that was in a thread about a month ago.

The NEC has, since the beginning of time, required a metal water service pipe (10 ft in the ground) to be used as an earthing electrode. It still has that requirement.

If the water service pipe is plastic (which yours may be) then different rules and different methods apply and metal interior pipes must be bonded.

Your statement, as a general rule, is simply false. Just like it was a month ago.

[JIMMIE]

As far as supplying electricity to a house a ground rod has no useful purpose other than saftey. Having one will not replace a broken neutral, not having one will not effect how well the electrical distribution in your house functions.

Jimmie

[John Grabowski]

*As someone else said the ground rod is not a substitute for a neutral. Neutral current wants to return to the power company transformer. To get there it normally travels over the neutral (Grounded conductor) wire. When the neutral wire is broken, but is bonded to the grounding conductor in the main panel, the neutral current will attempt to get to the transformer via the grounding conductor. However whether it makes it back to the transformer or not depends on the conditions. The transformer must have an unbroken grounding conductor connected to a ground rod in order for the neutral current to travel through the earth. There should also be a path of low resistance and that would depend on the soil conditions and distance.

I have heard stories from other contractors and inspectors of the neutral current from one house traveling through the earth to a neighbor's grounding conductor and going back to the transformer via the neighbor's neutral wire.

I hope that your BIL turned off the main breaker when he attempted to connect the ground rod. All of the return current could have been on that grounding conductor.

BTW the advice that you gave your BIL could have been fatal not only to him, but to someone who just happened to be walking on his lawn at that time. Also, If there was a pool nearby, although not likely this time of year someone in the pool could have gotten zapped from the stray current in the earth looking for a path to the transformer. He could also have damaged some appliances by having a higher voltage than normal passing through them The best advice in this case would have been to shut off the main breaker and get the neutral wire reconnected.

[zek]

The earth is just for safety. Local code here requires two ground rods and connection to water main. You need zero volts from you shower head to the drain. I got some volts one time long ago, when the water meter jumper was broken. The codes were also different then, at the same house.

[Limp Arbor]

Yes, he turned off the main and all of the individual breakers before trying this. Turned the main back on then each breaker.

How could someone walking by have been shocked? Doesn't electricity always seek ground?

BTW he also got the same advice from another guy who works at the power company. Obviously not as a permanent fix but to get his heat working til he could get the neutral wire reconnected.

So in my house as with most houses even though all of the neutrals and grounds are tied together in the panel everything is going back to the transformer?

[Limp Arbor]

You must have long leads on your meter to check across the shower head and the drain.

[trader4]

The unbalanced portion of the 240V service current wants to go back to the transformer via the neutral wire. If the service neutral is unhooked, it will attempt to go back via the ground connection and the earth. But exactly what path it takes is not determined. It depends on the resistance of the earth between the two point, and it's not going to be a beeline. If a swimming pool happens to bein that path, you could have parts of the pool energized, at least to some extent. Would it be likely to kill someone, probably not, but who knows?

I hope so. That's the only way to complete the circuit.

[Limp Arbor]

So I guess that is why you can't buy a "Worm Getter" anymore...

[dpb]

...

Some sections of the world where ground has a decent conductivity owing to mineral concentrations have actually used single-wire distribution in rural areas for cost-saving purposes where there is no return neutral; all is ground. (Some areas of Canada did; haven't been up there in 20+ years so not sure if all is yet gone or not...)

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[John Grabowski]

Yes, he turned off the main and all of the individual breakers before trying this. Turned the main back on then each breaker.

How could someone walking by have been shocked? Doesn't electricity always seek ground?

BTW he also got the same advice from another guy who works at the power company. Obviously not as a permanent fix but to get his heat working til he could get the neutral wire reconnected.

So in my house as with most houses even though all of the neutrals and grounds are tied together in the panel everything is going back to the transformer?

*Lightning goes to earth, neutral current goes back to the transformer. If everything is grounded and bonded to code and all connections are tight, all neutral current should travel back to the transformer via the neutral conductor. You can put an ammeter on the grounding conductor to see if any current is flowing. Unfortunately the meter won't tell you what direction it is flowing. If your neighbor lost his or her neutral connection you could have their neutral current flowing up into your panel and back to the transformer via your neutral conductor. This can be confirmed by shutting off your main breaker to see if the current flow stops. If it doesn't, talk to your neighbors.

I come in contact with a number of power company workers every year. I am always surprised at the questions some of them ask me about wiring in their own house. This past summer I had a guy ask me how he could do a service upgrade at his mother's house. The perception is that since they work for the power company, they know all about electricity. The fact is that they are very good at what the company trains them to do, but that does not include wiring a house or making a service change because the power company normally doesn't do that type of work.

[clare]

Because the ground connection is a very high impedence connection to the neutral at the power company.

[clare]

DEFINITELY all gone. Canadian electrical distribution safety requirements today are (generally) higher than those in the USA.

[Pete C.]

It would be difficult for them not to be. The NESC that US distribution is based on is pretty much all "it should be done this way unless you don't want to for some reason, in which case do whatever you want".

[Metspitzer]

I would bet they didn't find this problem with a meter. More likely who ever found this problem did a little dance.

[Pete C.]

The reference standards used for power distribution (NESC) and for residential and commercial wiring (NEC) are quite different. Utility personnel will be familiar with the NESC standards, but usually aren't familiar with the NEC standards to much extent.