AMPS in the cold water pipe

[fletcher]

I am a home inspector and one of my friends posted this photo on a home inspector board.

http://www.homeinspector.org/forum/forums/storage/8/5587/Amps.JPG

hope the link works.

If not, this is a photo of an amp meter (that encompasses the cold water pipe) showing a reading of 9.33

This is not a test that most home inspectors do so we don't know if this is a typical condition or not. Some guys claim some amps in the pipe is "normal" and some say there should be no amps at all.

The issue of "black copper" pipes were brought up. Some of us Home Inspectors think the black pipe means there is voltage running through the pipe causing the pipe to turn black.

I knew I could get the right answer here. Any thoughts?

 

[charlie b]

If not, this is a photo of an amp meter (that encompasses the cold water pipe) showing a reading of 9.33

I can’t tell from the photo, so let me ask. What scale is the meter set at? Is this 9.33 amps, or 9.33 milliamps, or 9,330 amps? There should be no amps on the pipe at all. But if the reading is much lower than one amp, then I would guess it is a stray reading that does not indicate a real problem.

Some of us Home Inspectors think the black pipe means there is voltage running through the pipe causing the pipe to turn black.

Sorry, but that is utter nonsense. The pipe was either black when it was manufactured, or it turned black due to the normal process of rusting.

 

[M. D.]

Maybe there should be no current however, with the multi-grounded neutral system there is almost always going to be some current flowing as it is a parallel path...

Now to find out if it is coming from this house shut the main off if the reading remains the same it is coming from elsewhere

 

[fletcher]

I am double checking with the original poster to see if he means milli amps or not.

Yes, I agree with the black pipe issue being nonsense. I left a piece in the back of my truck and it turned black from being rained on several times.

I will let you know what the original poster says.

 

[al hildenbrand]

You don't really state which water pipe you are looking at.

From the floor condition, the wood and the curve of the pipe, I assume that this Ammeter is clamped on within a foot or two of the water meter.

I also assume that the Grounding Electrode Conductor (GEC) from the Service Disconnect is connected to the water pipe on the opposite side of the Ammeter from the "street side" (the water utility or supply side).

If my assumptions are correct, then, I disagree with Charlie about the current reading of 9.33 Amps.

The power company routinely uses all connections to Earth as part of their distribution system. Current sources outside of the dwelling will "see" the GEC and the underground metal water piping as a return path.

Some of the current that is shown on the Ammeter will be the dwelling's own "unbalance current" returning to the local power supply (the power company local transformer).

Last, neighbor's unbalance currents will also be present, when the neighbors are connected to the same local transformer.

Without additional information about the specifics of the system shown in your photo, it is hard to make a judgment about the 9.33 Amps.

I do agree with Charlie that "black copper" is not factual.

 

[fletcher]

http://forums.mikeholt.com/showthread.php?t=90044

looks like this has already been discussed.

Al, what is the proper way to do this test? What readings should we be looking for on the meter?

 

[cschmid]

this is a topic of great discussions..a larger picture of the area would definitely be nice other wise we are all just making assumptions and we all know what assumptions lead to..

edited:is there a way to enlarge these pics with out having to save them to my puter..

 

[dereckbc]

Fletcher current on the water pipe is normal, in fact cannot be avoided in most circumstances. The reason is very simple the water pipe forms a parallel path of the system grounded circuit conductor back to a common transformer shared between two or more services (houses).

To take it one step further you can find current on the CATV coax for the same exact reason.

I am hesitant to even ask these questions but here goes:

1. Did you clamp the service grounded conductor and measure the current, and compare it with what was measured on the water pipe?

2, Would you even know what the numbers mean or what it tells you?

 

[al hildenbrand]

what is the proper way to do this test?

Given the wide variation of GEC connections in existing dwellings, I'd say, placing the Ammeter, as shown, being sure to clamp on pipe that is not jumpered (the water meter jumper is another parallel path), and that the Ammeter is on the street side of the GEC connection to the water pipe.

What readings should we be looking for on the meter?

Maybe adding a "fill-in-the-blank" is appropriate, given the rest of the information already in the home inspection report. Whether the power is on, or off; what types of electrical loads (AC, range, dryer, electric heat, etc.) are present, whether the home is occupied or vacant, etc., will "weight" the Ammeter reading. Interpreting the reading includes understanding the local power company distribution supply to the local transformer, understanding the neighbors associated with the transformer, and including a measurement of the inspected building's actual unbalance current.

I suspect that interpretation is not in your interest.

As a seat of the pants statement, for a 100 Amp 120/240 Volt residential urban electrical service, I'd wonder about a reading of 10 - 12 Amps and I'd investigate a reading around 15 Amps.

The fill-in-the-blank is nice 'cause many home inspections result in an electrician being brought to the premises anyway.

 

[al hildenbrand]

is there a way to enlarge these pics

If your browser is Internet Explorer 7, look in the lower right corner. . .there should be a magnifier with various settings there.

 

[charlie b]

is there a way to enlarge these pics with out having to save them to my puter..

In addition to Al's answer, if your mouse has a wheel between the left and right buttons, you can hold down the CONTROL key and rotate the wheel. This will zoom in or out, depending on which way you turn the wheel. If you look at the bottom right indicator that Al mentioned, you will see the degree to which you are zooming in or out.

 

[cschmid]

I like the wheel mouse and control key nice hot function..thanks guys that will help in the future..I find it funny I can program a robot and not know how to use the zoom features..now correct me if I am wrong with the amp clamp is that not the hundredth setting it is on so them are 9.1 amps..you notice i have not entered into this discussion yet..I need to go haul some pressure tanks now and will be back..

 

[fletcher]

Fletcher current on the water pipe is normal, in fact cannot be avoided in most circumstances. The reason is very simple the water pipe forms a parallel path of the system grounded circuit conductor back to a common transformer shared between two or more services (houses).

To take it one step further you can find current on the CATV coax for the same exact reason.

I am hesitant to even ask these questions but here goes:

1. Did you clamp the service grounded conductor and measure the current, and compare it with what was measured on the water pipe?

2, Would you even know what the numbers mean or what it tells you?

I have some people (electricians) saying it is normal. Some say it isn't. I didn't do the test, another inspector did so I have no idea how he did the test.

The fact that some electricians say this is normal and some do not.....and being that this sort of test is outside the scope of an ASHI or NAHI inspection anyway.....I think will continue to NOT do the test.

 

[infinity]

In addition to Al's answer, if your mouse has a wheel between the left and right buttons, you can hold down the CONTROL key and rotate the wheel. This will zoom in or out, depending on which way you turn the wheel. If you look at the bottom right indicator that Al mentioned, you will see the degree to which you are zooming in or out.

Doesn't work on my computer.

 

[dereckbc]

I have some people (electricians) saying it is normal. Some say it isn't. The fact that some electricians say this is normal and some do not.....and being that this sort of test is outside the scope of an ASHI or NAHI inspection anyway.....I think will continue to NOT do the test.

Matt any electrician who says it is not normal does not know what they are talking nor do they fully understand electricity and current flow.

The cold water pipe assuming it is metalic and a transformer is shared between two or more home, is in parallel with the service grounded conductor (aka neutral). Current takes all paths available and does not care if it is suppose to go there or not. When current paths are in parallel, current will flow no matter what. It is the same as putting two cable running to the same points, they will share the current based on the resistance of the path.

The only way to tell if it is a problem or not is to know how much current is flowing on the grounded service conductor vs. the water pipe. Otherwise any reading you take on the water pipe is meaningless.

 

[fletcher]

shock or no shock

shock or no shock

the guy to took the 9 amp reading has not answered me yet.

i asked him if he touched the pipe with the 9 amp reading or not. he claims he gets reading like this all the time and it is a chicago area thing? huh...seems like the law of physics would be the same in MI.

if you are reading 9 amps....shouldn't you get a shock from this?

 

[mikeames]

Fletcher.

I agree with the other posts if your trying to get something from this. Current on a metal water pipe is normal and like others stated electrician who tell you differently don't understand how utility transformers are wired in relation to a system.

IMHO: 9 amps is a bit much to be on the water pipe. I would personally try to find out more. Is it coming from within the house or from another house nearby. Like the post above stated turn off the main and see if the reading goes away if it does you have an issue in that house. If it does not don't worry about it.

9 amps flowing in the water pipe will not shock you. You could have 1000 amps flowing and it would not shock you. You are at the (same potential) "volts" when standing next to the pipe, and when your touching it you are exactly the same. The problem is if the water line was disconnected then you may / probably have a shock hazard. It is for this reason that bonding jumpers are required across a water meter.

 

[M. D.]

9 amps flowing in the water pipe will not shock you. You could have 1000 amps flowing and it would not shock you. You are at the (same potential) "volts" when standing next to the pipe, and when your touching it you are exactly the same. The problem is if the water line was disconnected then you may / probably have a shock hazard. It is for this reason that bonding jumpers are required across a water meter.

Not sure I can agree ,... if you grab the pipe with both hands a different points ,..now you are a parallel path and current will flow ,..if your wet and salty might be enough to kill,..even if not ,..I'm not sure I want even very small amounts of current running through my body...

shocking shower

 

[dereckbc]

i asked him if he touched the pipe with the 9 amp reading or not. he claims he gets reading like this all the time and it is a chicago area thing? huh...seems like the law of physics would be the same in MI.

:grin: No it is not just a Chicago thing

if you are reading 9 amps....shouldn't you get a shock from this?

No it shouldn't. There might be some potential if you were to cut the pipe and get between the cut ends. This is what some have refered to with plumbers and water utility workers.

A fully metalic water pipe system is double edged sword. In one since it does make for a safer system because if you were to loose your service grounded conductor (common problem), then the water pipe is going to be the return conductor and the customer is not going to notice a thing wrong and still be relatively safe (note your neighbor sharing the transformer may have problems though). However if a plumber or water utility worker opens the water line for whatever reason, they are in extreme danger.

If the water pipe is plastic between the meter and home, and the service grounded conductor opens up, chance are good thing like refrigerators, electronic equipment etc are going to be fried from overvoltages and possible fire hazard results. Ask any electrician about this

My last comment is unless you know how to diagnose and determine it is a problem, you shouldn't get involved. Because if you see 5 or 9 amps and write it up, then th ehome owner calls out an electrician to repair and finds it is normal. If I were the homeowner, YOU GET THE BILL.

 

[dereckbc]

Fletcher.

IMHO: 9 amps is a bit much to be on the water pipe. I would personally try to find out more. Is it coming from within the house or from another house nearby. Like the post above stated turn off the main and see if the reading goes away if it does you have an issue in that house. If it does not don't worry about it.

Mike maybe or maybe not. I don't think we should be telling a non-electrical professional if it is or not.

What if you were to measure the Service grounded conductor and it had 90 -amps, and the pipe was 9-amps? Is it a problem?

Now what if you measured say 10 amps on the service and 9 on the water pipe? Keep the answer to yourself, it is to make a point I think you and most understand.