Parking Lot Lights Questions

Midwestguy954

I'm going to wire 6 parking lots lights on poles that have been put up already and I have a couple questions. The lights are 120vac MH, poles are metal, bolted to new concrete pads. The installers have 2inch PVC underground from pole to pole, and are ready for me to pull in the wire. Do I need to sink in a ground rod at each pole, or is a properly sized ground wire back to the dist. panel in main building all that is needed? Is surge suppression required or a good idea? And if so would you recommend one at each pole or just at the dist. panel in main building. Is GFI protection required? Any other precautions that you can think of I would appreciate knowing. Thank You.

Speedy Petey

I don't know. What does 210.8(B) say?

__________________

Magnettica

I think a properly sized equipment grounding conductor (EGC) is all that he needs, but I would check with what the manufacturer of the light specs-out. My biggest concern for the parking lot lights would be voltage drop. Remember to size your EGC based on the size of your overcurrent protection, not the size of the wires going to each pole. No GFCI protection for me, thanx.

__________________
Electrician service in Rahway, Cranford, Clark, Westfield, Mountainside, Scotch Plains, Fanwood, Roselle, Roselle Park, and New Jersey | Same day electrical service and repairs | Licensed and Insured Electrician in Rahway

JohnJ0906

Don't forget 250.122(B)
If the circuit conductors are increased for voltage drop, the EGC must be increased.

__________________
John from Baltimore
"One Day at a Time"
All replies based on the 2008 NEC

Magnettica

Thanks John.

__________________
Electrician service in Rahway, Cranford, Clark, Westfield, Mountainside, Scotch Plains, Fanwood, Roselle, Roselle Park, and New Jersey | Same day electrical service and repairs | Licensed and Insured Electrician in Rahway

JohnJ0906

You're welcome.

__________________
John from Baltimore
"One Day at a Time"
All replies based on the 2008 NEC

Midwestguy954

Thanks for all your replies.

Bubbles

Just wondering the "why" of 250.122. Do you happen to know? EX. 4/0 200 amp service with only #6 to ground rod and #4 to water pipe. Good or bad analogy? Curious as to if the lights are on a 2pole 20 amp breaker and have #4's or #6's ran out to lights...why identical ground? It used to be 2 sizes below just a few years ago if I recall??

your friend

JohnJ0906

Think about this for a minute.

Why increase the wire size? Voltage drop.
What causes voltage drop? The resistance of the wire itself.
To reduce that resistance, and the voltage drop, increase the wire size.
Therefore, we might have #8 or #6 on a 20 amp circuit.

OK, now, why increase the EGC size?
What is the EGC for? Low impedance fault path. In a long circuit, the conductor resistance will affect the OCPD operation. Less amperage, longer to trip - or it might not trip at all.
The same reasons for increasing conductor size for the circuit conductors apply to the EGC as well.

__________________
John from Baltimore
"One Day at a Time"
All replies based on the 2008 NEC

JohnJ0906

Oh, and this is a very bad analogy. The Equipment Grounding Conductor and the Grounding Electrode Conductor are 2 different creatures - the GEC, and connecting to the planet Earth, has nothing to do with the operation of an OCPD at the <600 volt level.

__________________
John from Baltimore
"One Day at a Time"
All replies based on the 2008 NEC

Bubbles

Makes sense to me.

thanks