Bonding and Grounding Copper Pipes

[winnie]

I'm sure a similar tool is available in the US, but my google fu finds hardware from Australia:

Safety Meter Leads

• Unique screw up clamp ensures clamp cannot be dislodged if knocked or bumped <BR> • Individually tested and serialised <BR> • Insulated screwdriver style handle protects user yet provides easy to use clamp <BR> • 100 Volt heavy duty cable with sealed fixings <BR> • 205 Amp rating <BR> •...

www.cadia.com.au

 

[WasGSOHM]

Ask them for the Mean Time Between Failures, failures being for any reason.

Some component makers actually publish this number so consumers can do comparison shopping.

 

[Bro8898]

As I stated above, an open neutral situation can only be confirmed by taking measurements in the main service, requiring the services of an electrician.

Measuring current on the pipe you are cutting will give you a good idea of if there is a problem present, but cannot give a guaranteed result because as noted a low current might be the result of low neutral load.

IMHO what you should do as a plumber is to have a good set of bonding jumpers which you use to bypass any section of metallic service pipe which you may be cutting, and use those bonding jumpers religiously. Use something which can't be knocked off by accident.

Also, if you measure high current (several amps) on a pipe that you are about to cut, you might request the customer bring in an electrician.

Thanks for the response. Yes you did say that. Do you think car battery jumper cables would work for this? Also if I were to replace a section of metallic piping with pex and then remove the jumper would I be causing a problem?

I’m starting to understand that the electricity is trying to get back to the transformer and that the plumbing pipes become the path when there is an open neutral - but there’s no way I can know if there’s an open neutral. So I guess my questions in what situation would it be ok to make a repair with pex?

 

[Bro8898]

As I stated above, an open neutral situation can only be confirmed by taking measurements in the main service, requiring the services of an electrician.

Measuring current on the pipe you are cutting will give you a good idea of if there is a problem present, but cannot give a guaranteed result because as noted a low current might be the result of low neutral load.

IMHO what you should do as a plumber is to have a good set of bonding jumpers which you use to bypass any section of metallic service pipe which you may be cutting, and use those bonding jumpers religiously. Use something which can't be knocked off by accident.

Also, if you measure high current (several amps) on a pipe that you are about to cut, you might request the customer bring in an electrician.

Yes you did say that. Thanks for the response. Do you think car battery jumper cables would work for this? Also if I were to replace existing metal piping with pex and remove the temporary jumper cable, when would I be causing a problem?
I’m starting to understand that the electricity is trying to find a path back to the transformer and that it can use the pipes as a path if there is an open neutral (and there’s no way I can know if there’s an open neutral). So even if I use jumper cables on all jobs, I guess my question is this: at what point would it be a problem to replace metallic piping with pex? One thing to consider is even on piping systems that are all metal, the supply lines under the lavatory or kitchen sink (although they’re covered with that silver braided stuff) are normally made of some type of flexible plastic pex type material. So there’s definitely some break in the continuity of the piping in most houses (if not all) even when the entire plumbing system is metallic.

 

[Bro8898]

I accidentally posted that twice, sorry

 

[WasGSOHM]

An open neutral will have half the house getting dimmer and the other half getting brighter.

 

[WasGSOHM]

Some jumper cables save money by using weak springs which may not lower the contact resistance enough for the 200ADC they might pass.
I'd use a lightly sanded pipe with the wire under hose clamps.

 

[winnie]

Yes you did say that. Thanks for the response. Do you think car battery jumper cables would work for this? Also if I were to replace existing metal piping with pex and remove the temporary jumper cable, when would I be causing a problem?
I’m starting to understand that the electricity is trying to find a path back to the transformer and that it can use the pipes as a path if there is an open neutral (and there’s no way I can know if there’s an open neutral). So even if I use jumper cables on all jobs, I guess my question is this: at what point would it be a problem to replace metallic piping with pex?

I personally would not trust battery jumper cables; too much risk of then being knocked off.

If there is a problem, and you were to jump a chunk of metal piping, cut that pipe out and replace with plastic, and then remove the jumper, the problem would become apparent as you remove the jumper.

This comes down to your familiarity with the plumbing installs in a given area. A connection to soil will never carry enough current to be an issue. The issue is common metal piping systems. So if you know that the water main in an area is plastic, then even if the pipe into a building is metal you know that replacing a segment won't be an issue. But in a region with common metal supply piping, you can't really know if there is a problem when you break the piping circuit.

Jon

 

[kwired]

Keep in mind if conditions are right and it is the neighbor that has a bad neutral, it may be the neighbor that is going to see things burned up if you open his neutral that has taken the water pipe as a path and then back through the neutral where you are working at.

Also the rule to attach the grounding electrode conductor to the pipe within 5 feet of entry to the building didn't appear in NEC until about 1993 maybe 1996, can't remember for certain. Before then you could land it anywhere on the water piping that was convenient, but did have to use bonding jumpers around isolating sections or items that are likely to be removed such as a water meter if it was going to interrupt the path of/to the grounding electrode.

 

[roger]

Thanks for the response. Yes you did say that. Do you think car battery jumper cables would work for this? Also if I were to replace a section of metallic piping with pex and then remove the jumper would I be causing a problem?

I’m starting to understand that the electricity is trying to get back to the transformer and that the plumbing pipes become the path when there is an open neutral - but there’s no way I can know if there’s an open neutral. So I guess my questions in what situation would it be ok to make a repair with pex?

You can keep something like THIS on your truck to bridge the pipe when you have to cut it.

Roger

 

[winnie]

I am surprised that no one in the US makes something similar to the tool I posted in #21.

When I search for 'temporary bonding jumpers' I get links to tools that lineworkers use to jump lines that are grounded for work, not something for plumbers to use.

Bro8898: perhaps you can take the link in post #21 to one of your supply houses to see if they sell anything similar.

-Jon

 

[WasGSOHM]

You can keep something like THIS on your truck to bridge the pipe when you have to cut it.

Roger

It looks like that jumper can handle quite a few amps and some people might be interrupting a substantial number of amps.

 

[Bro8898]

I personally would not trust battery jumper cables; too much risk of then being knocked off.

If there is a problem, and you were to jump a chunk of metal piping, cut that pipe out and replace with plastic, and then remove the jumper, the problem would become apparent as you remove the jumper.

This comes down to your familiarity with the plumbing installs in a given area. A connection to soil will never carry enough current to be an issue. The issue is common metal piping systems. So if you know that the water main in an area is plastic, then even if the pipe into a building is metal you know that replacing a segment won't be an issue. But in a region with common metal supply piping, you can't really know if there is a problem when you break the piping circuit.

Jon

Wow that’s good information. I’ll be sure to purchase a jumper like the one you posted and not one made for a car battery. I’m sure I can find it somewhere.

So if a pipe is in the ground and both sides are buried in the dirt, then I don’t really have a risk of getting shocked? But will it still break the neutral path and damage equipment?

 

[Bro8898]

Keep in mind if conditions are right and it is the neighbor that has a bad neutral, it may be the neighbor that is going to see things burned up if you open his neutral that has taken the water pipe as a path and then back through the neutral where you are working at.

Also the rule to attach the grounding electrode conductor to the pipe within 5 feet of entry to the building didn't appear in NEC until about 1993 maybe 1996, can't remember for certain. Before then you could land it anywhere on the water piping that was convenient, but did have to use bonding jumpers around isolating sections or items that are likely to be removed such as a water meter if it was going to interrupt the path of/to the grounding electrode.

One of my earlier questions was regarding with side of pipe where the grounding electrode conductor lands that the plumber is working on. If it’s on the side closest to the street (where the pipe comes in the house from being underground in the yard) that is where I’ve seen jumpers over water meters and pressure reducing valves etc. However on the “house” piping side of where the grounding electrode conductor attaches I have not observed jumpers. Now that’s just what I’ve traditionally “seen” but it doesn’t necessarily mean anything because I observed it. So from a plumber’s perspective (at least what I’ve seen on jobs and been somewhat trained on, which again doesn’t meant anything) it would appear that I need to use a temporary jumper when replacing sections of pipe on the “street” side of the wire and make sure I go back with metallic piping in order to maintain continuity. But on the “house” side of the wire I can take pipes apart without the need for a jumper and go back with pex. BUT AGAIN I am now learning from the people that know on this forum that if a utility neutral has failed (which is something I have no control over and don’t have the knowledge to know if it has failed one way or another) then if I disconnect metallic piping anywhere in the house I run the risk of getting shocked and/or damaging equipment if not using a jumper. So I’m gathering that I need to use a jumper that’s made specifically for pipes on all jobs just to be sure. Does most of that sound about right to you?

 

[Bro8898]

I personally would not trust battery jumper cables; too much risk of then being knocked off.

If there is a problem, and you were to jump a chunk of metal piping, cut that pipe out and replace with plastic, and then remove the jumper, the problem would become apparent as you remove the jumper.

This comes down to your familiarity with the plumbing installs in a given area. A connection to soil will never carry enough current to be an issue. The issue is common metal piping systems. So if you know that the water main in an area is plastic, then even if the pipe into a building is metal you know that replacing a segment won't be an issue. But in a region with common metal supply piping, you can't really know if there is a problem when you break the piping circuit.

Jon

I made an earlier comment about supply lines under sinks and lavatories that look metallic because they’re covered in some type of silver braided material but it’s actually a covering around pex or some sort of flexible plastic. I’m pretty sure these little lines are not conductors and they’re installed in almost all houses. If a house lost its neutral wouldn’t these lines break the continuity of the metallic piping system? If so what would happen at that point?

 

[winnie]

Wow that’s good information. I’ll be sure to purchase a jumper like the one you posted and not one made for a car battery. I’m sure I can find it somewhere.

So if a pipe is in the ground and both sides are buried in the dirt, then I don’t really have a risk of getting shocked? But will it still break the neutral path and damage equipment?

If you do find a US supplier, please post a link here.

Even if both ends of the break are buried in earth there is still a potentially lethal shock hazard. In the worst case scenario we are discussing, the path back to the source is the common (meaning connected to multiple buildings) underground metal piping that you are cutting.

Jon

 

[winnie]

I made an earlier comment about supply lines under sinks and lavatories that look metallic because they’re covered in some type of silver braided material but it’s actually a covering around pex or some sort of flexible plastic. I’m pretty sure these little lines are not conductors and they’re installed in almost all houses. If a house lost its neutral wouldn’t these lines break the continuity of the metallic piping system? If so what would happen at that point?

These short lengths of non conductive pipe don't enter the picture because they are not between the underground water supply from the common metal water main and the point where the electrical system connects.

You need to think of the electrical path being broken. These fixture connections are not part of the path.

In a different scenario, imagine the incoming water supply is plastic. In this case an electrical system neutral failure is immediately noted, not masked by the plumbing system.

Jon

 

[winnie]

There are always bizarro possibilities, such as the electrical path being via some drain pipe in the house, or a water heater ground wire being the connection.

But in general the risk is from the electrical system 'Grounding Electrode Conductor' going to the pipe, and the street side of that connection. In general there isn't risk on the house side of the connection, with the caution that in the past the connection could be anywhere in the building, and people used to use plumbing as grounding all over.

Jon

 

[Bro8898]

There are always bizarro possibilities, such as the electrical path being via some drain pipe in the house, or a water heater ground wire being the connection.

But in general the risk is from the electrical system 'Grounding Electrode Conductor' going to the pipe, and the street side of that connection. In general there isn't risk on the house side of the connection, with the caution that in the past the connection could be anywhere in the building, and people used to use plumbing as grounding all over.

Jon

Great. Now that is good information. So generally, if you were working on the street side of the connection (meaning the place where the wire attaches to the pipe), you would use the appropriate jumper cables that are made for plumbing and replace the damaged piping back with metallic pipe? But on the house side of the connection it’s ok to work without a jumper and replace with pex?

I mean that’s what I always generally assumed and am here for confirmation. I’ve just heard horror stories (and fortunately never been a part of them) where someone disconnected a water heater or cut into a pipe and an arc occurred or they became part of the path.

But if I can go by that general rule that you discussed above, I think that’s good enough for me.

 

[winnie]

Like I said, there are bizarre possibilities but that is the general rule.

I'd suggest getting a clamp on current meter as a cheap fast check for the bizarro situations.

Jon