lightning rod question

[William E. Siegel]

These lightning rods are attached to the air condenser units on the roof. What effect, if any, will this have on the units if one of these rods takes a hit??

[phinsperger]

I would imagine that it is not approved by the manufacture and the warranty is void weather or not lightning hits it.

[rwand1]

http://www.inspect-ny.com/lightning/lightning.htm

http://www.lightningrods.biz/Instruc...ions_pg_2.html

Dumb in my opinion to put the rods on the a/c units.

[Thomas H. Dietrich]

My understanding is 'lightning rods' are working 24/7. They constantly pickup (and sometimes discharge) unbalanced air/ground charge. So if they are doing their job, there would be less strikes.

tom

[George P. Wells]

Originally Posted by wsiegel

These lightning rods are attached to the air condenser units on the roof. What effect, if any, will this have on the units if one of these rods takes a hit??

The rods will afford a great deal of protection to the AC units in a lightning strike. Units without rods on them are at a much greater risk of damage than those with rods on them.

The lightning rods and cables will shunt the lightning around the AC units. The tendency for the electricity to go around the AC units is called the Faraday Effect. This is the same reason that you should stay inside a metal body automobile when there is lightning present.

The rods will act as a shunt around the AC units. This is essentially, what is supposed to happen when a surge protector is used to protect electronic equipment (though they do not work very well at all). Surge protectors (usually metal oxide varistors, i.e. MOV's) provide a shunt around the device being protected.

Lightning rods should be located at the highest points possible and atop any sharp or protruding objects to have the best chance of redirecting a strike. It is almost essential to have lightning rods on rooftop units in high lightning activity areas such as Florida.

[rwand1]

Isn't Florida ligthtening captial of the USA?

[Frank P. Newman]

Based on papers I heard several years ago at IEEE meetings, I doubt that the rods shown are sufficiently tall or well enough insulated from the A/C units on which they sit to offer much protection. A direct strike would likely blow up both units.

Some lightning protection systems do attempt to bleed off atmospheric charge, but the ones I have seen installed at weigh stations, etc. along the Florida interstates are very tall and are topped with what looks like an umbrella with lots of ribs and points, but no fabric. Some people swear by them whele others consider the guy who developed them to be a 'quack'.