[gwilkrrs]

hello- my question comes from an addition that was built 3 years ago. we recently had cable tv installed and the tv shows wavy lines and you can hear a hum on the set. Direct tv (same location) doesn't do this nor does regular tv. this is using AV cables, when we switched to an HDMI cable it got better with less interference but it didn't go away.
the cable installer said I needed to ground the new cable he pulled from the pole. I installed a ground rod and he grounded the cable to it. the problem was still there but it did improve.
the installer was on the phone for awhile and came back and said I had a leaky neutral in the house. he said the cable is grounded/bonded with our electric company from the pole and when it is plugged in the box is searching for the electric co's ground because the house isn't sufficient. he suggested I use a generator to supply power to the cable box to see if it solves the issue and then if it does I should trouble shoot the circuit the outlet is on.......
I have never had this problem before with my electronics but I have never had cable here either........
I have not tried a generator or other outlet to test as this is a back up service and we rely on satalite. I do wish to fix if trhere is an electrical issue though.
how do you trouble shoot a circuit for a leaky ground? I used an outlet tester and everything checked out.-----

 

[joed]

I installed a ground rod and he grounded the cable to it.

You should have grounded it to your existing grounding electrode. Separate ground rods are not correct or code.

 

[jbfan]

Another know nothing cable installer.
When was the house built?
You did nothing by installing the ground rod, but waste time and money.

 

[gwilkrrs]

the house was built in 1951-
10 years ago the house was updated, this work included a new meter, panel and outlets.

the area in question is a 3 year old addition that has all new electrical.

 

[AllanJ]

Run a #6 copper wire, outside the house as much as possible, connecting the new ground rod to the existing ground rod.

The neutral network in your electrical system is (should be) connected to (bonded to) the grounding system (grounding electrode system) at the panel where the first master (whole house) disonnect switch or breaker is located.

For most homes the electric company ground is the same wire as the electric company neutral that is strung from the utility pole and usually has the hot wires wrapped around it. This is also connected to the grounding electrode system at the aforementioned panel.

Many TV and radio interference problems can be fixed by running an additional ground wire daisy chained among the various electronic items (TV, A/V receiver, etc.) connected to the chassis of each. The same stud that you screw the cable end onto is one exposed part connected to the chassis. Connect the far end of the wire to a known ground which could be panel neutral. You can take a chance and connect the far end of the wire to a nearby radiator although if this does not work, extend the wire to the panel ground before drawing any conclusions.

 

[Know A Little]

Hum bars as you described are usually a result of the Equipment Grounfd Conductor carrying current. This current is generally from a neutral to ground connection downstream from the main service. Though it can be from a 240 volt load such as a resistive heater with one side shorted to ground (the one energized leg not connected).
In either case you need to locate the “Bootleg” neutral or load issue.
AS this involves working in an energized panel an electrician that knows what he is doing should look at this.

With as much load on as possible and the hum bars present
1. They would perform a zero sequence test on the main feeder (measure the current in all three incoming conductors simultaneously, the reading should be zero.
2. Measure the current on the neutral to ground bond connection.
3. Turn off circuit breakers one at a time until the Hum Bars disappear.
4. Unplug all the equipment on this one circuit.
5. Isolate the circuit that cleared the hum bars and megger neutral to ground and “hot” to Ground reading should be above 1 megohm.
6. Divide and conquer, start in the middle and test and move on until you locate the issue.
7. Lastly if you find nothing look at the appliances you had connected to this circuit.

 

[Know A Little]

Many TV and radio interference problems can be fixed by running an additional ground wire daisy chained among the various electronic items (TV, A/V receiver, etc.) connected to the chassis of each. The same stud that you screw the cable end onto is one exposed part connected to the chassis. Connect the far end of the wire to a known ground which could be panel neutral. You can take a chance and connect the far end of the wire to a nearby radiator although if this does not work, extend the wire to the panel ground before drawing any conclusions.

That does not fix the problem, it will mask the problem IF this issue is the result of a grounded neutral downstream from the main service neutral to ground bond. Which in my experience 95% of hum bar issues are. To mask a neutral to ground short is never a wise decision, though many take this path.

 

[gwilkrrs]

So I spoke with my electrician and he had me look at rhe meter on th house.
Power comes from the pole to the meter, from the meter it goes into a disconnect before going into the house to the panel. There is no ground rod at the meter area. The panel is grounded to an old well casing under it in the basement.
He thinks that a wire should leave the disconnect and go to a ground rod under the disconnect/meter. He also thinks the hot and cold lines off the water heater should be bonded together.....

Thoughts?

 

[Jim Port]

Your house may pre-date the use of ground rods and only be grounded to a metal water line.

 

[Know A Little]

So I spoke with my electrician and he had me look at rhe meter on th house.
Power comes from the pole to the meter, from the meter it goes into a disconnect before going into the house to the panel. There is no ground rod at the meter area. The panel is grounded to an old well casing under it in the basement.
He thinks that a wire should leave the disconnect and go to a ground rod under the disconnect/meter. He also thinks the hot and cold lines off the water heater should be bonded together.....

Thoughts?

While you can do this it won't fix the problem and the ground rod does not need to be near the meter. Bonding the water lines, no problem there.

I left off one item that should be checked.

Assuming you are on city water (you said OLD WELL) I would check for current on the water piping particularly at the location of the water meter.

It is possible to have circulating current on the water lines from neighbors houses, sharing a metallic water piping system and utility transformers.

The list I made above is a starting point and a GOOD electrician has to be involved, one that has a variety of basic test instruments.

 

[gwilkrrs]

so yes, grounded to an old well casing in the basement- but we are still well water not city water, the new well is outside in the yard.

the house has cvpvc water lines not copper, but the house has a dual pipe heat system (radiators) with metal pipe through ought.

another tidbit---- the area in question is an addition. the entire addition is fed from a subpanel off the main panel- so it is power from pole to meter, meter to disconnect, disconnect to main panel, main panel to sub panel, sub panel to addition.

when I spoke to the electrician he said the above systematic testing was sound advice- he said to run an extension cord to an outlet to the main house (not the addition) to see if it is isolated to the addition (subpanel) or service problem effecting everything.

he said the exterior ground rod is a cya move and thinks the interior ground to the well is good but may need to be supplemented......

 

[Know A Little]

so yes, grounded to an old well casing in the basement- but we are still well water not city water, the new well is outside in the yard.

the house has cvpvc water lines not copper, but the house has a dual pipe heat system (radiators) with metal pipe through ought.

another tidbit---- the area in question is an addition. the entire addition is fed from a subpanel off the main panel- so it is power from pole to meter, meter to disconnect, disconnect to main panel, main panel to sub panel, sub panel to addition.

when I spoke to the electrician he said the above systematic testing was sound advice- he said to run an extension cord to an outlet to the main house (not the addition) to see if it is isolated to the addition (subpanel) or service problem effecting everything.

he said the exterior ground rod is a cya move and thinks the interior ground to the well is good but may need to be supplemented......

Check and see if the subpanel neutral is grounded, generally a GREEN SCREW through the neutral termination bar or a small metallic strip bolted to the back box and terminated on the neutral termination bar. Though there may be other means. The Neutral SHOULD NOT be grounded in this subpanel

Also the feeder to the sub panel should be 2-hots. 1- neutral and a ground conductor. The neutrals and grounds cannot be terminated on the same termination bar.

The extension cord is a good start.

 

[Jim Port]

The subpanel in the attached addition does not need a ground rod. The ground should be at the service.

 

[AllanJ]

The purpose of a "ground wire" daisy chaining among the pieces of equipment is to create a common reference (bonding; equipotential conductor) among those pieces including their chassis. The cable company equipment should be included among those pieces. There is no easy way to prove that the cable company equipment got included although grounding to the building electrical ground (grounding electrode system) and/or connecting up the coax cable will usually accomplish this.

The existing fat wire from panel to well casing acts as (acted as) the grounding electrode conductor to a water pipe exiting the house underground.

If there was no ground rod then the the new ground rod you added together with #6 copper wire to the main panel brings you closer to current code, which requires two ground rods at least 6 feet apart (under some obscure circumstances just one ground rod).

 

[brric]

Did the cable guy install a coaxial grounding block similar to this:

 

[bernie963]

...and if the coax ground block is there, did he run a ground wire to a know good ground. The ground wire goes in the hole held by the machine screw on the ground block...

bernie

 

[gwilkrrs]

Yes that is what the cable guy installed- the ground wire then went to the ground rod that I planted.
I will look into the subpanel in a bit but right now is storm preparation of equipment

 

[AllanJ]

Known good ground means the electrical system ground or something bonded to (having an essentially resistance free connection with) the latter.

If A is bonded to B and B is bonded to C then A is bonded to C.

So connecting a #6 wire (maximum size ever required from a ground rod) from your new ground to the main panel will complete this path.

Grounding of antennas, telephone wires, coax cables, etc. is commonly done using a bracket of the type pictured above or a bracket of a similar character, but the bracket is always bonded to the electrical system ground.

 

[gwilkrrs]

the cable and the power are on opposite sides of the house.
what is the max distance a #6 wire can run for ground?

 

[AllanJ]

No limit is specified for how long the wire (grounding electrode conductor) used to connect a ground rod may be and still be #6 in size.