pole base requirements?

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bradleyelectric

bradleyelectric

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Location
forest hill, md
Does anyone have information as to general quidelines for light pole bases? I'm looking at a design build job with 4- 14' poles with 175W single shoeboxes. I'm thinking 4' 18" hole with rebar every foot copper rod driven down and encased in the base. base to be flush with the ground. Any input would be appreciated.

steve
 
Pole Base Requirments

Pole Base Requirments

I have installed a lot of poles in Florida and usually we have an embedment detail either from electrical engineer or pole manufacturer to follow that answers all these questions. Check with your local AHJ for special requirments such as wind loading.
 
We set a few poles. Why don't you go ahead and go 72" below grade on your base. You did not say how far above grade the top of the base would be. Most of ours in a parking lot are 28" up to 36" in some cases. We use whatever size Sonotube for the pier dameter. We usually set 24" piers but with that small a pole I think 18" would actually look better. This stuff is all based on a 90 mph wind rating on the polesfor this area. We would probably never get that unless a tornado hit. My reason for the extra depth is this. You are only taking about $15 more in concrete, the digger truck will probably charge the same price for the hole, the rebar will add about $4 or so. So we go just a little deeper just for a safety factor. But if you must get an engineer involved to make you feel safe then do so. Of course all these additional costs we add to the price we submit. Just a thought.
 
You can delete the copper ground rod. The steel and the concrete will have a low resistance to lighting and will not be damaged in a lighting strike. I have a IEEE study from the early 1960s that documents this. I think Mike Holt has this article somewhere on his web site.
 
cowboyjwc said:
Your numbers sound good, but you do have to design with a wind load factor in mind. We design for 80 mph here.
Click to expand...

Yes, I need to figure for about 90 M/H wind. I did state that the base would be flush with the ground. They are going in a flower bed next to gravel parking lot in condo community. Condos are on the water, built on stilts and the bottoms are finished off as garages. It's more like just gravel drives, not parking, and they are just trying to put a little light on the side of each building without lighting up peoples windows. How do you design for wind factor?

Steve
 
Sorry Steve, I don't know how you design for it. I always rely on the engineer and our structural plan checker to make sure that it's right. Most engineers will tell you that light pole bases are usually over engineered.
 
Check with the local AHJ. Out here we are required to provide engineering by a licensed PE for the pole foundations. Things considered include hieght, weight, profile, fixture type/weight, windload, soil conditions etc. I have rarely seen the foundations fail but I have seen several poles go over in the wind because someone put big add banners on them and the poles weren't designed for that.

Bob on the left coast.
 
Whoops! I forgot to add my two cents!

We install 20' poles with 175W MH heads on 24" bases with 4 foot deep poles. They don't tip. That's my entire wealth of knowledge on the matter. :D

One note: They have a 10" footprint, I think, and the j-bolts supplied with the poles will not fit in a smaller sonotube effectively. You might check that before the pour, how large your 14' pole's footprint is, with the j-bolts sticking away from the pole.

For an additional two cents, I will supply you with my handy dandy concrete calculator that I whipped up on my PDA. It's an excel spreadsheet. ;)
 
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