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Old 04-21-2013, 06:07 AM   #16
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connecting ground bars between two houses


I say there is no problem+ connecting a fat ground wire* (#6 in this situation) from the fat ground wire attached to the ground rod at one house to the fat ground wire attached to the ground rod at the other house. You need to have it protected from physical damage.

It is not unheard of for cable TV supplier equipment to not be properly grounded. With appropriate grounding on your own equipment (such as a separately run ground wire I suggested earlier) you greatly reduce the chances of damage to your equipment when the coax cable from improperly installed cable company equipment is attached.

* If it connects a ground rod or other qualifying grounding electrode to some other electrical component then the fat ground wire is called a grounding electrode conductor. If at least one end is connected to a non-electrical item for example it connects the inlet and outlet of a water heater, then it is called a bonding jumper.

+ Some experts say that for any given house there should not be bonding to grounding electrodes in different places even on opposite sides of the same house. They use the term "single point grounding" which theory I do not understand. But outbuildings such as detached garages will need ground rods if there is a subpanel out there which blows that theory.

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Last edited by AllanJ; 04-21-2013 at 08:37 AM.
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Old 04-21-2013, 07:35 AM   #17
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connecting ground bars between two houses


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+ Some experts say that for any given house there may not be bonding to grounding electrodes in different places even on opposite sides of the same house. They use the term "single point grounding" which theory I do not understand.
I've never heard of that, but I have seen it done when the utilities are on one side of the house, and the CATV is on the other side of the house... IF both these grounding rods are not bonded together, you can/will get an audio hum.

I had this exact scenario happen at my house, once I bonded the rods together, no more hum. I'm pretty confident this is what is happening in the OP's case.
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Old 04-21-2013, 10:48 AM   #18
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connecting ground bars between two houses


Alan, you are saying he can run a bonding wire from house #1 to house#2?

I don't think that is legal, but I can't prove it right now.
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Old 04-21-2013, 04:46 PM   #19
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connecting ground bars between two houses


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Alan, you are saying he can run a bonding wire from house #1 to house#2?

I don't think that is legal, but I can't prove it right now.
People on a code forum would seem to agree with you. One says the following:
[connecting the ground of each house together] is a band aid to address your issue, but during a fault condition, that your equipment may not even cause, the amount of current imposed on the conductor could even exceed that of a 750mcm. The fault condition could come from the utility. Remember, that when you tie two different ground sources together, you are effectively tying the neutrals, from different sources, together as well. One service could experience an open neutral. What affect do you think that would have on your #6?

Are you even sure that both houses are fed from the same utility transformer? By interconnecting the ground references from different structures, you could be affecting the utility companies infrastructure. Not a good Idea.
Which puts me back to square one. FWIW I agree with what stickyboy has said -- bonding the two ground rods together should level the potential and eliminate the ground loop. But the above advice suggests this is a dangerous solution. Not sure where to go from here.
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Old 04-21-2013, 04:49 PM   #20
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connecting ground bars between two houses


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Which puts me back to square one. FWIW I agree with what stickyboy has said -- bonding the two ground rods together should level the potential and eliminate the ground loop. But the above advice suggests this is a dangerous solution. Not sure where to go from here.
They are all bonded together anyway, but you should bond the COAX at both structures. This will basically do the same thing as bonding the ground rods together.
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Old 04-21-2013, 05:17 PM   #21
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connecting ground bars between two houses


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People on a code forum would seem to agree with you. One says the following:
[connecting the ground of each house together] is a band aid to address your issue, but during a fault condition, that your equipment may not even cause, the amount of current imposed on the conductor could even exceed that of a 750mcm. The fault condition could come from the utility. Remember, that when you tie two different ground sources together, you are effectively tying the neutrals, from different sources, together as well. One service could experience an open neutral. What affect do you think that would have on your #6?

Are you even sure that both houses are fed from the same utility transformer? By interconnecting the ground references from different structures, you could be affecting the utility companies infrastructure. Not a good Idea.
Which puts me back to square one. FWIW I agree with what stickyboy has said -- bonding the two ground rods together should level the potential and eliminate the ground loop. But the above advice suggests this is a dangerous solution. Not sure where to go from here.
That's certainly an accurate description of a potential fault condition that can occur. However, it is not a valid reason not to bond the signal grounds (coax shield) at each structure. The fact is that the fault you describe can occur any time there is a data utility service to a structure in addition to power. When an open utility neutral happens, all hell breaks loose and lots of bad things happen. One of those bad things is that your cable TV coax shield tries to carry your home's neutral current. This overheats it and can make the whole run back to the cable utility box start smoking, or even burn through. This problem is no better or worse when you run between houses instead of to a cable utility's gear - the exact same risk exists. Bottom line: the coax shield is REQUIRED to be bonded at each house. This is a safety requirement which prevents the cable TV line and attached equipment from becoming electrified by a ground fault. It also prevents attached equipment from being destroyed if a condition occurs where the coax shield carries fault current. As an added benefit, bonding the coax prevents the hum issue by ensuring that the signal ground is at the same potential is the AV equipment ground.
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Old 04-21-2013, 06:43 PM   #22
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connecting ground bars between two houses


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That's certainly an accurate description of a potential fault condition that can occur. However, it is not a valid reason not to bond the signal grounds (coax shield) at each structure. The fact is that the fault you describe can occur any time there is a data utility service to a structure in addition to power. When an open utility neutral happens, all hell breaks loose and lots of bad things happen. One of those bad things is that your cable TV coax shield tries to carry your home's neutral current. This overheats it and can make the whole run back to the cable utility box start smoking, or even burn through. This problem is no better or worse when you run between houses instead of to a cable utility's gear - the exact same risk exists. Bottom line: the coax shield is REQUIRED to be bonded at each house. This is a safety requirement which prevents the cable TV line and attached equipment from becoming electrified by a ground fault. It also prevents attached equipment from being destroyed if a condition occurs where the coax shield carries fault current. As an added benefit, bonding the coax prevents the hum issue by ensuring that the signal ground is at the same potential is the AV equipment ground.
This sums it up, bond the COAX jacket at each structure and your problem will disappear.

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