Thread: Home Grounding
View Single Post
Old 03-08-2011, 11:23 AM
DaveInDenver's Avatar
DaveInDenver DaveInDenver is offline
Hard Core 4+
Join Date: Jun 2006
Location: Larimer County
Posts: 8,471

I think it's important to distinguish between equipment damage and safety. I think we can all agree that if a radio or computer dies due to a discharge, that it sucks but isn't critical. If a person is killed or hurt or a house is burned down, that is critical.

We can also agree that an antenna that works well for RF signals is going to be conductive and tall, also making them better at lightning attraction!

OTOH, if you think about it, they are also very good to have around because they can protect your house. This requires that you consider the equipment damage potential because you in a way make the antenna the conduit to route lightning away from the house. Which means that you need to think about the current flow and don't do something to make it neutral or worse. This is why I want to put lightning arrestors in a box on the outside of the house connected to a ground rod.

When placing protective device consider the case where they are destroyed, there is a lot of energy in a lightning strike and it has to go someplace. Think about what would happen if a device arced over say near a gas line or where you store paint. Most houses would sustain non-structural damage in a strike, like you mention blowing off bricks or localized burning. But if the strike hit your gas line that creates a secondary problem which isn't really a direct electrical effect per say.

One thing is that the chance for shock is low with a lightning strike unless you are touching the antenna or equipment during the actual strike. A small window of time. However, an electrically floating antenna during a storm, really anytime, can build a large charge that can be painful or fatal, not to mention damaging. The static needs to be bled off even during normal conditions, so all external antennas should be grounded. This, though, has to be a DC ground and not an RF ground. Your radio does not like to see an RF short (although an antenna tied hard to ground is not necessarily an RF short at the radio end). Also there is a non-trivial chance that antennas can carry commercial power, so before touching them make sure they are not touching overhead wires, underground wires or otherwise. That is the main shock danger, that a loose wire touches your antenna.
'91 Pickup - Imelda
'08 Tacoma TRD - Donna

"The Only Thing That Is Constant Is Change." -- Heraclitus
Reply With Quote