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The Something Awful Forums > Discussion > Hobbies, Crafts, & Houses > Wiring Thread: This stupid safety device started alerting that there wasn't safety!
 
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Cheesemaster200
Feb 11, 2004

Guard of the Citadel

Big Steveo posted:

De-rating of cables is a mixture of several factors: Whether it is installed underground, in conduit, surrounded by thermal insulation and bunching with other circuits.

That picture is something I have been taught not to do, I would usually run 2 cables in a 25mm hole and then other circuits run in parallel in their own holes. That prevents 2 things; overheating and de-rating of the cables, and when running the cables they will tend to rub against the insulation of the other cables which could cause damage to the insulation of the cables.

NEC states you do not have to derate if you are running through a nipple which is less than 24" in length as long as you still meet required fill.

The above picture does not meet 40% fill requirements for conduit, however I am not quite sure how romex is handled in residential installations. Either way it doesn't look like a good idea.

Data cables also do not count as a current carrying conductor, and (theoretically) do not count towards fill calculations either.

* # ¿ Apr 28, 2009 23:40
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# ¿ Apr 30, 2024 21:49
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Cheesemaster200
Feb 11, 2004

Guard of the Citadel

grover posted:

Grounding is extremely important for antennas, as they tend to act as lightning rods, and proper grounding will dissipate the static charges that build up, and reduce the change of being struck by lightning. What you're literally doing is running a wire from this antenna into typically an 8' (or longer) rod stuck in the ground - this "grounds" your system, and dissipate any electrical energy right into the earth. The ground wire of your electrical system is always grounded, too. The risk is lessened if there are higher actual lightning rods around, but not eliminated. Does your building have lightning protection on the roof?

If your antenna is just a piece of wire dangling from the balcony, there's no grounding possible, you can't ground a monopole antenna. You can ground other types of antennas, though. If you're using a commercial high-gain antenna with a metal body, you need to ground the metal body to a ground point. You should use a grounding block to ground the shield of the coax, too. Often, the easiest one is the ground prong in your electrical system, but to do it right, you'd run a grounding conductor directly to the structural steel of the building. If you have a metal balcony railing, that metal balcony railing should already be grounded- if you can verify that it's grounded, it'll make this was easier.

If he is on the 20th floor of a building, I would sure as gently caress hope they have a lightning protection system.

How big is this antenna he wants to put up on his balcony, and how many floors are above him?

* # ¿ May 19, 2009 02:01
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The Something Awful Forums > Discussion > Hobbies, Crafts, & Houses > Wiring Thread: This stupid safety device started alerting that there wasn't safety!