Grounding issue in CATV system

[Impatience II]

I am at a loss here on how to help this customer. Looking to pick some minds to see if anyone has run into this situation before.

A technician was called out to the customers home because of an interruption of service to the customer. Upon investigation, the customer noticed that the cable was melted on the drop side of the ground block. The technician noticed that the ground was to the cold water pipe located in the customers basement about 8 feet away from the ground block. The ground block was located on the outside of the home next to the power meter. The technician replaced the customers service drop and relocated the ground to ground rod approx. 3 feet from the ground block. The technician utilized an amp clamp to check the cable sheath. Upon doing so he recognized that the was getting over 2 amps. The technician notified the customer of the issue and recommended that an electrician come out to investigate the issue. The area power company was also contacted to ensure that the neutral to the home was intact.

The customer contacted their electrician who stated that there was not an issue. The power company also did not find any problems with their feed to the home. Therefore, the customer called us back out there.

Upon the request of the service tech, my supervisor dispatched be out to the home to work with the service tech on finding the issue. Here is what I found:

1) Amperage only appears on the drop side of the ground block (.41A)
2) When the ground is disconnected from the ground block, the meter reads .02
3) The ground was originally run past a ground block to another one. I move reran the ground to a closer ground rod. Both rods are connected together.
4) We had the customer turn on air conditioners inside the home. Upon doing so our readings increased upwards of 1A.
5) The technician and the customer claim that they both have seen readings >4A, I was unable to confirm this.
6) I went to an adjacent customer fed off of the same tap and found that the readings on their cable were at .02.
7) I also made a makeshift ground using some ground wire. I striped the wire approx 4' and stuck it into the ground. I connected it to our ground block and had a reading of .02A on the amp clamp.

I believe that the customer is still having an issue inside their home electrically, as our system is not capable of passing >.5A through the tap. However, with the customer receiving information from their friend electrician, it has been a tough sell.

We decided to leave the ground disconnected from the ground block until the customer was able to get his electrician out tot he home. We were called back out today for the cable again being melted at the side of the home. The customer is going to contact the electrician again so we can all meet out there at one time. I would like to be prepared with some knowledge before hand.

Any help is greatly appreciated.

 

[Little Bill]

When you say "ground rods" are you referring to the rods installed for the electrical service?

Have you clamped the GEC (grounding electrode conductor) to see if there is current flow on it?

Have you tried unplugging the cable box inside, then checking the current on the cable?

What about unplugging all the TVs and checking?

I won't get into other possible things to check with the electrical since you are not an electrician.

 

[Impatience II]

I am referring to the rod that the electrical service is using.

 

[don_resqcapt19]

...
1) Amperage only appears on the drop side of the ground block (.41A)

That would be the only part of the cable system that is connectected in parallel with the grounded conductor of the electrical system, and would indicate the problem in on the line side of the electrical service disconnet.

2) When the ground is disconnected from the ground block, the meter reads .02

Yes, now there is no parallel path for the grounded conductor current.

3) The ground was originally run past a ground block to another one. I move reran the ground to a closer ground rod. Both rods are connected together.

As long as the rods are connected together by a bonding jumper it shouldn't make any difference.

4) We had the customer turn on air conditioners inside the home. Upon doing so our readings increased upwards of 1A.

Are the air conditioners 120 volt or 240 volt?

...
6) I went to an adjacent customer fed off of the same tap and found that the readings on their cable were at .02.

Indicates that the problem is the electrical service neutral for the house in question.

7) I also made a makeshift ground using some ground wire. I striped the wire approx 4' and stuck it into the ground. I connected it to our ground block and had a reading of .02A on the amp clamp.

That is a high impedance path and the impedance limits the current.

I believe that the customer is still having an issue inside their home electrically, as our system is not capable of passing >.5A through the tap. However, with the customer receiving information from their friend electrician, it has been a tough sell.

I would expect the problem to be on the line side of the service disconnect.
What happens to the current on your grounding connection if you turn the main breaker off? What happens if you put as much load as you can on one of the "phases" and at the same time as little load as possible on the other? Has the homeowner had any issues with lights getting brighter or dimmer? Have the electrician check the line to neutral voltage at the main panel as the loads are changed.

 

[Impatience II]

I am going back out to this house today to meet with the customer and their electrician. I am of the understanding that his air conditioners are 120v units. However, I will check while I am there today.

I will recommend to the electrician that we preform some of the steps that are outlined below to see what we get for an outcome.

I have not noticed any dimming of the lights as the ground is removed. I have had customers in the past where this has occurred and it was always a broken neutral.

Thank you for the assistance.

 

[Impatience II]

Just a little followup.

Went back out to the customers home and met their electrician. The electrician was pretty confident that the issue was not related to the electrical service and came off as being quite cocky. He didnt even pull out a tool until I recommended that he go into the house and kill the main breaker to see if the amperage on the line dissipated. Upon doing so he went and grabbed a flashlight. Upon flipping the breaker the meter read around .01A. It was finally at this point that he attention was grabbed and he went to go and get a tool belt. He turned on breakers one by one until we saw the meter begin to register readings. The readings were quite significant (in the area of 11-18A). During this process a loud popping sound began to occur at the meter box, the lights also dimmed in the customers house and their washing machine began to smoke. The electrician pulled the meter head and inspected the box. He was unable to find any issues there. The power company was called to the home. They put a blank face plate over the meter socket and order a replacement meter head. Its now been well over a week and I have not heard anything from the customer. Until hearing further, I am going to assume it was the meter head that was the source of the customers issues.

If I hear more I will report back...

Thank you all for your help.

 

[ActionDave]

You got yourself a neutral problem. Based on what you have said above it seems like the home owners electrician does not know what this is. Time to find a better electrician.