# pole base info



## racerjim0 (Aug 10, 2008)

I have a small job to put three 20' parking lot poles in with 400 watt heads. The customer wants me to do the pole bases. I have looked through some old plans for specs because I know I've seen them before but I must have tossed those.
I plan on using 24" X4 ft each sonotube, three re-bar rings and 4 vertical pieces of re-bar. (less than 1 foot will be out of the ground and this is middle Tennessee so its all surrounded by rock and I know there will be concrete mushrooming out of the bottom)
Questions:
What size re-bar?
Are 3 rings enough?
Are 4 verticals enough?
And where the heck is the section in the code book about the ground rods? I know its in there.


----------



## raider1 (Jan 22, 2007)

Usually the pole base will be engineered and the engineer will specify the amount and and size of the required reinforcing bars.

As for the ground rod requirement take a look at 250.32(A) specifcally the exception to that section.

Chris


----------



## 220/221 (Sep 25, 2007)

I just read that yours will be almost flush mounted so disregard my 30" high specs. I assume yours are not in a parking area. If they are, you need to reconsider and use a taller base to protect the poles.

In any case, you need 6' depth and you don't need the sonotube to go all the way down, just enough to secure it and keep it clean a few inches below grade.




Our standard rebar cage for a 20' 4" pole is: 

18" round

8' tall (appx 6' below grade and 2' above) 

Has 4 vertical #5 (5/8") "legs" 

and 12"x #4 (1/2") rings every 12 inches.

Our standard sonotube is 24" diameter by 36" tall (30" high with 6" below grade).



Don't install a ring at the very bottom and it will be easier to adjust the cage height withour the bottom ring hitting the dirt..

Ground rods not required but it's not a bad idea to attach a #4-#6 to the cage with an acorn and leave a stub to the handhole.

Have your holes dug @ 24" round and 6' *plus *deep. It's way easier to put dirt in than take it out.

Put your cage in place and set it close to proper height.

Install your conduit in and out keeping the cage plumb and centered in the hole.. Keep the conduits coming stright up and centered in the cage. 

Make sure your PVC 90's are glued on tight. When in doubt, tape them in place. You don't want to have one pull loose while you are pouring concrete. Make sure the cage won't put pressure on the conduits when the concrete is being poured. Don't set the cage on the conduits. Give yourself some slack. 

Install the ground wire (if applicable) to the rebar. Leave enough wire to go down 30" and back up with the conduits. Tape it in place (to the conduits) This will keep it out of the way when you install the anchor bolts.

Build a 2x4 aquare frame and drywall screw it to the sonotube, about 6" from the bottom. Slip the tube in place to check the fit and clearances.

Whan it's time to pour, level the sonotube and make sure the cage is plumb. You will have about 3" clearance on the outsides and about the same on top. 


I prefer a dry mix if I am only doing a couple/few pole. If the concrete is too wet, you will be there for hours waiting to finish it.


Pour slowly keeping hold of the cage with one hand. Make sure the cage doesn't start to tweak. It is impossible to wrestle back in place after the halfway point. Make sure the sonotube stays level/plumb during the pour. Once it has been poured, if it's level, it won't move. If it gets out of whack and gets filled, it will keep leaning and will end up really ugly. It is possible to correct a filled base by putting your shoulder into it but it's better to simply avoid thar situation.

Watch closely as it nears the top and cut the flow or you will end up shoveling up hauling away concrete that you paid good money for.

Use a baseball bat to strike the edges around the tube to achieve a relatively smooth finish. I've used all kinds of tools but the low tech bat seems to work as good as anything. The dryer the mix, the more you want to beat on it. Don't gently tap it. It's not fragile. You will not break the sonotube . The more you tap it, the better the results will be.

Use a dywall mud mixer (big potato masher) on top to push down the aggrigate and bring up the workable concrete.

Push your templated anchor bolts into the concrete. If it's not too wet, they will stay in place. If it is too wet, they will want to sink and you will have to wait or support them with a couple pieces of 1/2" EMT under the template. Don't set the bottom bolts into the concrete. They shouls land right above it.

This should have gone up there somewhere but......unless you have a good solid template, make your own from 1/2" plywood. Some companies provide crappy, thin Masonite templates which will not hold the bolts securely. Do not attemp to ues them. Spend a few minutes and save a lot of grief. When attaching the anchor bolts to the template, turn all the L's the same direction, 90 degrees from each other so you end up with a square pattern. If you point them in or out, they will catch on the cage or the conduits.


Crap. That took forever. I could have done it already.


----------



## racerjim0 (Aug 10, 2008)

No engineering here. This is a mans parking lot for his tractors, boats, etc.


----------



## 480sparky (Sep 20, 2007)

racerjim0 said:


> No engineering here. This is a mans parking lot for his tractors, boats, etc.


So you're willing to take the hit in the ol' wallet if a pole falls on his $500,000 boat?


----------



## 220/221 (Sep 25, 2007)

racerjim0 said:


> No engineering here. This is a mans parking lot for his tractors, boats, etc.


 
Here is some value engineering, tennis court style.

Use 24' x 4" galvanized shedule 40 poles (posts) supplied from a fence company. Dig holes 12" round and 4' deep. Pipe wrap the post to above grade, set in place and concrete in place.

Come back an drill the pole a couple feet above grade, install a wp box and run conduit between boxes, drop wires (or cable to be compliant)down the pole and be done with it.


----------



## racerjim0 (Aug 10, 2008)

220 221, Man sorry you did all of that typing. I've put up hundreds over the years but always just stuck my templates in the mix, the sonotube/rebar was always done by the GC and I never really paid much attention to their cage. I did tell the man that I would prefer to go higher with the concrete but he wants it just high enough so that a mower won't mess it up. 
Digging in this part of TN is sometimes a chore even with a backhoe. You end up with a hole wider than it is deep sometime. There always seems to be a 3 foot boulder right where you didn't want it
The last big parking lot I did had spec's that included a ground bar, probably overkill. Oh well. 

Thanks, you can have the rest of the day off!!


----------



## amptech (Sep 21, 2007)

I always do the 5/8" rebar cage withe the anchor bolts welded to the cage. First ring is welded 20" from the bottom. Put 12-16" of pit run in the bottom to shove the cage legs into to adjust the overall height. 6'6" deep hole for 18-25' square steel tapered poles in your wind zone(TENN).


----------



## Malaking_TT (Dec 17, 2010)

why don't you just buy some fiberglass light poles? Just dig a hole about 3' deep and bury it. I thought they were hack at first but we put them in a few apartment parking lots and AFAIK they are still standing.


----------



## erics37 (May 7, 2009)

Malaking_TT said:


> why don't you just buy some fiberglass light poles? Just dig a hole about 3' deep and bury it. I thought they were hack at first but we put them in a few apartment parking lots and AFAIK they are still standing.


I've been working for my current company about 4½ years, and literally EVERY SINGLE YEAR, we get a call from a particular apartment complex that has those fiberglass poles, saying that another one of them fell over. Usually just due to high wind gusts (they're set pretty far back from the parking spaces).

Every time we've gone out there we've offered to do an estimate on replacing the fiberglass poles with real poles with concrete bases, but they aren't interested. They'd rather keep having us install those fiberglass pieces of crap.

I think they're down to two or three original fiberglass poles. We'll probably be replacing them soon. And then we'll probably start having to replace our own poles. :laughing:


----------



## MDShunk (Jan 7, 2007)

Many of the pole companies can fax you a generic foundation print for your area. I know my area wants engineer sealed detail prints on the pole foundations. I'm nearly certain that all coastal areas want engineer sealed prints on light foundations also.


----------



## raider1 (Jan 22, 2007)

MDShunk said:


> Many of the pole companies can fax you a generic foundation print for your area. I know my area wants engineer sealed detail prints on the pole foundations. I'm nearly certain that all coastal areas want engineer sealed prints on light foundations also.


Also areas that have high wind velocities and high seismic zones will most likely require engineered stamped drawings for the pole bases.

Chris


----------

