Transmission Lines & Electrical Code
 

I have a new house and my main concern is not having my homeowner's
insurance nullified in the case of fire because of my ham radio setup.

I have regular coax running 100 watts through the attic.

1)Is this a violation of the National Electrical Code?

NA4G wrote:

"The National Electrical Code requires 4 inch creepage distances
and clearances between any transmitter conductor inside the building
and normal interior electrical lines. It also requires 2 foot clearance
between antennas and leadins and any other electrical lines outside.
It also requires 3 inch creepage and airgap distances beween the the
antenna and leadin lines and any building surface. The requirement
for the ``insulating support'' is nonabsorbent treated pins or brackets
with insulators having not less than 3 inch creepage and airgap distances.
(reference N.E.C. Section 810)."
( From: Robert D. Keys )
Subject: best stand offs for ladder line?




Newsgroups: rec.radio.amateur.antenna
Date: 1998/04/02 )

I may wish to go to higher power, maybe 1000 Watts and run ladder line (450
Ohm window-line) outside the house.
3-inch standoffs outside the house are a cosmetic problem.

2) Is there a safe way to run the ladder line through portions of the attic?
What about housing it in 1" PVC pipe and maintaining at least 4 inch
creepage distance within the attic? Is PVC prohibited in the attic?

3) If a 3-inch airgap distance is required between the leadin lines and any
building surface, wouldn't that require at least a 6-inch hole in the wall
of the building to bring the line in? There must be another explanantion...

I'm sure this sort of thing has come up in the past!

"gibberdill" wrote in message
...
I have a new house and my main concern is not having my homeowner's
insurance nullified in the case of fire because of my ham radio setup.

I have regular coax running 100 watts through the attic.

1)Is this a violation of the National Electrical Code?

NA4G wrote:

"The National Electrical Code requires 4 inch creepage distances
and clearances between any transmitter conductor inside the building
and normal interior electrical lines. It also requires 2 foot clearance
between antennas and leadins and any other electrical lines outside.
It also requires 3 inch creepage and airgap distances beween the the
antenna and leadin lines and any building surface. The requirement
for the ``insulating support'' is nonabsorbent treated pins or brackets
with insulators having not less than 3 inch creepage and airgap distances.
(reference N.E.C. Section 810)."
( From: Robert D. Keys )
Subject: best stand offs for ladder line?




Newsgroups: rec.radio.amateur.antenna
Date: 1998/04/02 )

I may wish to go to higher power, maybe 1000 Watts and run ladder line
(450
Ohm window-line) outside the house.
3-inch standoffs outside the house are a cosmetic problem.

2) Is there a safe way to run the ladder line through portions of the
attic?
What about housing it in 1" PVC pipe and maintaining at least 4 inch
creepage distance within the attic? Is PVC prohibited in the attic?

unfortunately i don't have a copy of the code at home and don't often use it
for this type of stuff anyway. but if the creepage distance is what i seem
to remember, that is the length of the insulating standoff that is holding
the wire. so no, putting it in a 1" pipe wouldn't work, you need to have a
3" or 4" creepage length insulator.... creepage length if i remember right
is measured along the surface of the insulator, so if the surface has
grooves or ridges it is actually longer than the straight line length. hard
to explain, but it measures the length a current would travel if there was
dirt or moisture on the surface of the insulator. the requirement for a 3"
airgap would mean you need at least a 6" + wire spacing conduit with the
wire held in the center by appropriate length insulators.


3) If a 3-inch airgap distance is required between the leadin lines and
any
building surface, wouldn't that require at least a 6-inch hole in the wall
of the building to bring the line in? There must be another
explanantion...

yeah, except as noted above, if the wire spacing is 1" for the ladder line
the hole would be 7" by 6"... great fun these codes aren't they!


I'm sure this sort of thing has come up in the past!

Unless you intend to run 10 kilowatts of RF power, try to completely forget
all about your hopelessly imagined problems. Don't lose any sleep. Just use
ordinary electric wires and cables and run them wherever you fancy. Just
like domestic 110-volt power cables.

I've been running 100 watts over 20-gauge plastic insulated wire through
1/8" holes in dry, inflammable, wooden window frames for nigh on 25 years
and never yet burned the house down.

Thank you for your reply.

Actually, I am not afraid that I will start a fire.

I am afraid that a fire might start for some other reason, and that my
insurance company won't pay my claim because of unrelated code violations.

So again, let me ask:

What must a homeowner do regarding ham transmision lines so as to avoid code
violations?


"Reg Edwards" wrote in message
...
Unless you intend to run 10 kilowatts of RF power, try to completely
forget
all about your hopelessly imagined problems. Don't lose any sleep. Just
use
ordinary electric wires and cables and run them wherever you fancy. Just
like domestic 110-volt power cables.

I've been running 100 watts over 20-gauge plastic insulated wire through
1/8" holes in dry, inflammable, wooden window frames for nigh on 25 years
and never yet burned the house down.

The requirements for amateur radio stations are in Article 810 of the
NEC. My copy of the NEC is 14 years old, so I wouldn't want to quote it.
A google search of

NEC 810 amateur

produced quite a few hits, some with direct quotes from the NEC. I
suggest you take a look at a few of them. Considering how seriously you
take the matter, and the possible cost of doing it wrong, I don't think
you should depend on newsgroup answers to your question. You should see
for yourself just what the NEC says.

I also suggest that you contact your city, county, or state electrical
inspection department. It's possible that one or more of those
jurisdictions have requirements differing from, or going beyond, the
NEC. They also might have a copy of the NEC and local codes that you
could look at and/or photocopy. And, they should be able to answer any
questions requiring interpretation.

If your electrical inspection office can't provide a copy of the NEC for
you to look at, you might consider shelling out $100 - $200 to buy one.
It doesn't change much from year to year, so you might be willing to
settle for a previous year's copy which I'm sure you can find at a
substantially reduced price. Or, excerpts might be available at a lower
price yet -- a web search would be the best way to find them.

Roy Lewallen, W7EL

gibberdill wrote:
Thank you for your reply.

Actually, I am not afraid that I will start a fire.

I am afraid that a fire might start for some other reason, and that my
insurance company won't pay my claim because of unrelated code violations.

So again, let me ask:

What must a homeowner do regarding ham transmision lines so as to avoid code
violations?

"gibberdill" wrote in message
...
I have a new house and my main concern is not having my homeowner's
insurance nullified in the case of fire because of my ham radio setup.

I have regular coax running 100 watts through the attic.

1)Is this a violation of the National Electrical Code?



The ARRL hand book has a few paragraphs on this. It seems that if the coax
is grounded you are ok. If not coax then the wire needs to be sujpported 3
inches from the walls on insulators and comes into the building through an
insulated tube.

Group:

I just got a flyer from NFPA for the 2005 NEC. Pre release special $65

--
Crazy George
Remove N O and S P A M imbedded in return address

Actually, I am not afraid that I will start a fire.

I am afraid that a fire might start for some other reason, and that my
insurance company won't pay my claim because of unrelated code violations.

So again, let me ask:

What must a homeowner do regarding ham transmision lines so as to avoid
code
violations?

===================================

Yes, I now understand.

Everything depends on your insurance company's policy on what tricks they
employ to avoid paying claims. So the best place to enquire is at your
insurance company.

On the other hand, the probability of the exact circumstances ever arising
which would invalidate a claim is smaller than you, personally, winning the
National Lottery.

All of life is a gamble. You can't cross the road without the risk of being
run over by a bus. But in this particular very narrow case the odds are on
your side.

And you don't want to spend the remainder of your life trying to calculate
the exact probabilities before erecting your antenna. Don't keep the DX
waiting! If you are still a little aprehensive, just keep a bucket of water
and a bucket of sand handy in the attic.
----
Reg