Adding new ground rod

Smith333 · Jun 24, 2008

The cable TV (broadband) and antenna lightning supressor are grounded on the copper water line of my house. The problem is that we installed a water softener with plastic connections, so the grounding no longer exists. On top of that, the grounding points are on the opposite side of the house as the softener and well service entry point.

I think I have two options. I could drive a new grounding rod through the basement concrete floor and into the subsoil. Or, I could run about 100 ft of conductor (not sure which AWG) all the way to the service entrance and ground there. Which is the better idea?

Mikey · Jun 24, 2008

Generally, you want the ground path as short and straight as possible. That's a vote for the hole in the floor, but unless the basement ceiling is well over 10' it'll be tough to drive standard rod(s).

I'm a little confused about the water softener installation. If it was just inserted into an existing copper system, it should have been jumpered with a bonding connection from one side to the other to maintain the circuit.

Sponsor · 2022-01-29T12:20:58-0800

Billy_Bob · Jun 24, 2008

There is a thing called a "ground loop"...
http://en.wikipedia.org/wiki/Ground_loop_(electricity)

Therefore it is best to have a "central point of ground" and everything is grounded to this point.

Can you place a grounding jumper between to two stubbed out copper pipes going to the water softener? This is done with water heaters to connect the hot and cold lines...
http://www.allthumbsdiy.com/images/hot-water-heater-tank/remove-ground-wires-v1.jpg

Chris75 · Jun 24, 2008

JAR8832 said:
The cable TV (broadband) and antenna lightning supressor are grounded on the copper water line of my house. The problem is that we installed a water softener with plastic connections, so the grounding no longer exists. On top of that, the grounding points are on the opposite side of the house as the softener and well service entry point.

I think I have two options. I could drive a new grounding rod through the basement concrete floor and into the subsoil. Or, I could run about 100 ft of conductor (not sure which AWG) all the way to the service entrance and ground there. Which is the better idea?

First off, the catv must be bonded within 5' of the water entrance, so must the service disconnect if using the metal underground water pipe as an grounding electrode. with that said, I would just install a jumper around the water softner which you should have done anyways if you read the directions that came with the unit...

If you insist on installing a ground rod you MUST bond that ground rod with the power grounding electrode with #6 AWG copper.

Chris75 · Jun 24, 2008

Billy_Bob said:
There is a thing called a "ground loop"...

Therefore it is best to have a "central point of ground" and everything is grounded to this point.

A ground loop is the least of worries when it comes to bonding the grounding electrodes together...

Bob NH · Jun 24, 2008

Definitions:
Grounding Electrode - The metal device such as ground rod, or metal water service line, or other conductor in the earth that meets the code requirements.

Grounding Electrode Connductor - The conductor that ties the ungrounded conductor (the neutral) to the Grounding Electrode.

Service - The main disconnect point where the main power enters the house

If the Grounding Electrode is a metal water pipe serving the house then the Grounding Electrode Conductor from the Service must be connected to the Grounding Electrode (the metal water pipe) within 5 ft of where the metal water line enters the house.

The size of the Grounding Electrode Conductor depends on the size of the main breaker but need not be larger than 6 AWG if the Grounding Electrode is a ground rod.

I am traveling and don't have my code with me but I recall that there is a mximum distance from the service entrance to a ground rod that is to be used as a Grounding Electrode.

The ground of the CATV should be connected to the Grounding Electrode System or Grounding Electrode Conductor. The cable wires usually enter the house near where the power enters the house and the ground is usally attached near the Service panel. Can't cite; no code available.

Chris75 · Jun 24, 2008

Bob NH said:
I am traveling and don't have my code with me but I recall that there is a maximum distance from the service entrance to a ground rod that is to be used as a Grounding Electrode.

No maximum distance, but one would think shorter is better.

Bob NH said:
The ground of the CATV should be connected to the Grounding Electrode System or Grounding Electrode Conductor. The cable wires usually enter the house near where the power enters the house and the ground is usually attached near the Service panel. Can't cite; no code available.

Not always, but usually. At my house the electric is on the opposite side of the house from the catv drop.

Bill Arden · Jun 24, 2008

The more the merrier.

But... the ground rod needs to be in conductive soil and there is no guarantee that the ground below the slab is conductive enough.

I would suggest adding a ground just outside near where the CATV enters and run a short wire in.

That ground then has to be connected to the main ground rod with heavy enough wire so that it does not overheat during a lighting event.

I don't know what code requires, but I'm guessing 12ga would be good enough.

The only problem with multiple ground rods is keeping the wires between them heavy enough to handle any currents that might occur.

Adding more ground rods will also reduce "ground rise" during a lighting event and thus reduce the voltages that get past the protector.

So... The more the merrier.

Chris75 · Jun 25, 2008

Bill Arden said:
That ground then has to be connected to the main ground rod with heavy enough wire so that it does not overheat during a lighting event.

I don't know what code requires, but I'm guessing 12ga would be good enough.

Its #6 AWG.

Mikey · Jun 25, 2008

All the CATV grounding fittings I've seen have holes sized for #8.

Bill Arden · Jun 25, 2008

Mikey said:
All the CATV grounding fittings I've seen have holes sized for #8.

The wire between ground rods has to be heavier than the one going to a specific surge protector or grounding fitting.

I am going to guess the #6 AWG requirement comes from the service current rating so that either ground rod wire could handle the fault current caused by a lost neutral wire.

pudge565 · Jun 25, 2008

Bob NH said:
Definitions:
Grounding Electrode Connductor - The conductor that ties the ungrounded conductor (the neutral) to the Grounding Electrode.

Can't beleive nobody else saw this the neutral is the grounded conductor the hot is the ungrounded.

Mikey · Jun 25, 2008

I think Bob was just seeing if we were paying attention.

Chris75 · Jun 25, 2008

Bill Arden said:
I am going to guess the #6 AWG requirement comes from the service current rating so that either ground rod wire could handle the fault current caused by a lost neutral wire.

I'm not sure I understand your statement? grounding the electrical system is for limiting voltage imposed by lightning, line surges or unintentional contact with higher voltage lines... thats it...

Chris75 · Jun 25, 2008

Mikey said:
All the CATV grounding fittings I've seen have holes sized for #8.

Thats because all you need is #14 to ground the CATV wire, the #6 is for bonding two electrodes together if you happen to drive a rod for the CATV system...

Clear as mud?

Mikey · Jun 25, 2008

Chris75 said:
Clear as mud?

About that

. I was just musing over the voltage drop in a 10' run of 6AWG copper during an average lightning stroke of 40,000 - 300,000A... Of course, some claim the real purpose of a lightning arrestor is not to carry the full impact of a lightning stroke, but to gradually bleed off potential so that the stroke never occurs.

Chris75 · Jun 25, 2008

Mikey said:
About that . I was just musing over the voltage drop in a 10' run of 6AWG copper during an average lightning stroke of 40,000 - 300,000A... Of course, some claim the real purpose of a lightning arrestor is not to carry the full impact of a lightning stroke, but to gradually bleed off potential so that the stroke never occurs.

What do you mean by lighting arrestor? The device you can buy, or a ground rod?

The reason we only need #6 to a ground rod is because thats all the earth is good for anyways... any wire bigger than that would be useless.

Mikey · Jun 25, 2008

We must have especially good dirt here in Lightning Alley... my house came with a lightning rod system and the downleads are about 5/8" stranded aluminum.

"Lightning arrestor" was a poor choice of terms. "Lightning protection system" is better, but still bogus, I think.

Chris75 · Jun 25, 2008

Mikey said:
"Lightning protection system" is better, but still bogus, I think.

Probably, since nothing will protect your home from a direct strike.

Bob NH · Jun 25, 2008

I goofed on the grounded vs ungrounded conductor. The Neutral is the GROUNDED couductor. Brain wasn't working on that one.

Adding new ground rod

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