Ground outdoor MV security light?

[EJohnson]

Hello everyone;

I bought a 175W mercury vapor secuirty light and I want to install it next to my above ground pool. My plan is to buy a 4x4 16' treated lumber or use a 2" 20' metal fence post pipe (which I already have) to use as a pole; -4 feet into the ground (soil).

I plan to connect it to the GFCI outlet which my pump/filter is plugged into. The circuit is on a 20 amp breaker (12/2 UF) which runs from my garage's sub panel; underground about 40+ft. to the GFCI. Now i'm worried that if I install this light that high in the air; it might become a great lightning rod!!! Right? Especially if I use the metal pipe as the pole. What should I do (ground or no ground)? Also, I don't run the pump at night so these (light and motor) aren't going to be on at the same time. Thanks, Johnson

[John Grabowski]

You can alleviate the lightning concern by driving a ground rod adjacent to the pole and connect it with #8 or #6 copper wire.

Make sure that the light does not hang directly over the pool.

[EJohnson]

Should I still use both #12 ground wire that is with the 12/2 UF cable AND the #8 or #6 ground rod too OR just the #6 and ground rod? Infact; this light is going to be about 14ft. in the air so it's not likely someone would touch it. I decided to use the wood 4x4 post; Afraid that the hot wire would get pinched inside the metal pipe and become energized. Bad situation by a swimming pool!!! Johnson

[John Grabowski]

Use both ground wires as they will each provide different functions. The #12 will be effective in tripping the circuit breaker if there is a ground fault. The #6 connected to the ground rod will enable lightning to go directly to earth without affecting your home's wiring.

[PipeDown]

12' is not all that high unless you are in the middle of a golf course. If lightning is going to hit that spot, there is little you can do about it. Directing the current into ground (via another ground wire aside from the one to the GFCI) protects the structure but sidestrikes (to people and bathers) from roots and underground pipes can still occur.

Naturally, you should NEVER use your pool when lightning is around anyway even if it has not started raining.

Poolwater with all that chlorine is generally plenty conductive.