I'm helping out a friend with a new house who wants to add surge
protection. The plan is to use a whole house AC surge protector at
the panel and a seperate cable coax surge protector located a few feet
away where the cable enters the house.
The question is, how to tie the seperate coax protector to the house
ground? There are actually two 150 amp panels next to each other.
The service comes into a long narrow metal box between the two panels,
which in turn feeds the two 150 amp panels. There is a heavy gauge
copper ground wire that runs from this narrow metal box into the
concrete basement slab. So, what is the correct, code compliant
method to bond to this?
Can I buy some type of bolt on connector that I can slip over the
exposed existing ground wire outside the box and secure another ground
wire to it and then run over to the coax protector? That would seem
to me to be the preferred method, if permissible.
Or can I bond to the ground inside one of the breaker panels and run a
ground wire from the panel out to the coax protector?
It really depends on your local codes but common practice is to
use a split bolt to bond the coax protector to the #4 copper
ground wire coming out of the power panels. You can also run it
to the ground rod and use another rod clamp for your protector
ground wire. Some city/county engineering departments may have
requirements that are more strict than the National Electrical
Code or I've come across some that are very slack. I've worked
in some areas where there was no inspection except for the
power company. You might call your local inspector and just ask.
All of them I've ever met would be glad to tell you their local
requirements. As far as running it into the power panel, all of
your cable/telecom installers are not going to open your power
panels and will always look for an external connection.
On Wed, 31 Mar 2010 05:45:55 -0700 (PDT), email@example.com wrote:
I would suggest moving into the 21st century and install an inter
system grounding block. (2008 code)
This is a terminal strip that has a "lay in" lug for the grounding
conductor you are talking about and several terminals for attaching
other grounding conductors.
The home store should have one but any electrical supplier will if
On Mar 31, 11:22 am, firstname.lastname@example.org wrote:
Actually the house was built in the 21st century, only 4 years ago.
But I guess they finally updated the code to something logical that
all new homes should have.
Anyway, thanks for the help. That is exactly what I need. A little
googling produced this:
If I was doing it, I would just use a split bolt as others have
suggested. You want to minimize wire length to the common connection point.
If the "coax surge protector" is just a ground block, which is used
where cable enters the house, it doesn't include surge protection. The
voltage on the center wire can rise until it arcs across at the F
connector - about 4kV. There are cable surge protectors (which may be
what you have).
You are installing the service panel suppressor at one of the 150A panels?
Generally keep the leads from the surge suppressor short.
The wire to the slab should be a "concrete encased electrode", commonly
called a Ufer ground. It is one of the better ones.
How's that work when the ground is a line tied to the foundation rebar
instead of a rod? Cause that's how a lot of new construction is being
done now. Can you attach near the point the line goes into the block?
That's exactly what the inter-system grounding blocks are designed
for. I guess the remaining question is if anyone is going to bitch
about exactly how close to the grounding electrode one places the
grounding block. In my case, the logical place would be right
beneath the panel, about 4 ft. which seems reasonable to me. I could
mount it lower, but then I'd have to secure another plywood mounting
board to the blocks. Much easier if I just put it under the panel.
Don't see that it makes any difference anyhow, as the total length of
wire from the cable coax surge protector or anything else that gets
connected to ground is going to be the same anyway.
The NEC generally requires a concrete encased electrode (Ufer ground)
for new construction. (It also still requires using a water pipe as an
electrode if there is 10 ft of metal in the earth.)
My only suggestion, which I gave before, is generally to minimize the
length of earthing wire from panel to the block and from the phone and
cable entrance protectors to the block. Sounds like you are doing fine.
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