pole light bases...

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emahler

Senior Member
just did a search for some info on sizing a concrete base for a pole light...came across a post by MDshunk where he stated something to the effect of "it's not like anyone is going to try to put 2' of concrete in the ground for a 20' pole"..and his rule of thumb was basically 1' down for every 5' up...i.e. a 20' pole would get 4' buried...

well, i'm here to say that Mark was wrong...we recently had a pole hit in the parking lot of one of our customers...the base was knocked over pretty good...when we went to dig it up to straighten it out, we received a nice little surprise...

poles are 25' with 2 shoebox heads...base is 30" diameter...base is 2' 6" above the ground...and we learned that when they installed it, they buried literally 15" of base in the ground...

so to be clear, they had a total of roughly 4' of concrete base, and 2' 6" of that 4' was above the asphalt...

good times...
 
mcclary's electrical

mcclary's electrical

Senior Member
Location
VA
emahler said:
just did a search for some info on sizing a concrete base for a pole light...came across a post by MDshunk where he stated something to the effect of "it's not like anyone is going to try to put 2' of concrete in the ground for a 20' pole"..and his rule of thumb was basically 1' down for every 5' up...i.e. a 20' pole would get 4' buried...

well, i'm here to say that Mark was wrong...we recently had a pole hit in the parking lot of one of our customers...the base was knocked over pretty good...when we went to dig it up to straighten it out, we received a nice little surprise...

poles are 25' with 2 shoebox heads...base is 30" diameter...base is 2' 6" above the ground...and we learned that when they installed it, they buried literally 15" of base in the ground...

so to be clear, they had a total of roughly 4' of concrete base, and 2' 6" of that 4' was above the asphalt...

good times...
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,,,,,they were asking for a disaster
 
cadpoint

cadpoint

Senior Member
Location
Durham, NC
Just because they didn't use someone equation doesn't make that someone wrong. Per the stated equation it'd be 5 feet underground, seems the orginal installer had no interest in doing it right and the quoted stater did nothing wrong. JMO...
 
mcclary's electrical

mcclary's electrical

Senior Member
Location
VA
cadpoint said:
Just because they didn't use someone equation doesn't make that someone wrong. Per the stated equation it'd be 5 feet underground, seems the orginal installer had no interest in doing it right and the quoted stater did nothing wrong. JMO...
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I didn't read his statement to "blame" MD,,,,but rather I read his statement as,,He referenced the measurement to prove these pole were underengineered
 
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emahler

Senior Member
cadpoint said:
Just because they didn't use someone equation doesn't make that someone wrong. Per the stated equation it'd be 5 feet underground, seems the orginal installer had no interest in doing it right and the quoted stater did nothing wrong. JMO...
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cad - don't misunderstand...mark simply stated that no one was dumb enough to not use enough concrete under the ground....i found someone who was:D
 
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emahler

Senior Member
mcclary's electrical said:
Are you engineering the new bases? What are your plans?
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do a walk through and get some information...then have them engineered if the customer wants...otherwise, we just did a project 10 miles a way with essentially the same poles, with engineered bases....2'6" above ground, 4' below ground, rebar, etc....i would be fine using that design for these poles...
 
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satcom

Senior Member
Ok, whenever you are going to install parking lot lighting poles, do it right and have a licensed PE to spec out the design, and give you a sealed detailed plan, the applied top moment will generates lateral soil pressures that usually govern the design, the footing can typically have a depth/width ratio of 2:1 and greater, it's just something you estimate for on a pole lighting project, wind load, and soil conditions, and top loads will vary from project to project, hire a PE, up front.
 
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hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
Most of the engineered pole bases here in Georgia require 8' below grade, that being said, we had some windy weather last year that blew over a couple of poles on a brand new Cracker Barrell, the contractor had less than 2' below grade (uncompacted backfill too). Apparently the bases did not get inspected, or the inspector did not know what he was doing. These were at least 30-36' poles. I had something new on some poles I put in earlier this year, the plan reviewer with the city called for straight anchor bolts. The manufacture had to custom make them.
 
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220/221

Senior Member
Location
AZ
vegasmark said:
we did about fifteen 36' poles last summer with 18' of concrete underground. it was for a motocross track.
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Yikes!

I hope they were 48-60" diameter. 18" aint gonna hold a 36' pole for very long.

We dig up our share of shallow bases. It's always a nice bonus because it's a pain to pull them out or chip them off below grade.

Our standard is 24" diameter, 6' below and 2.5' above grade. About 1 yd of concrete.
 
qcroanoke

qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Sorta retired........
220/221 said:
Yikes!

I hope they were 48-60" diameter. 18" aint gonna hold a 36' pole for very long.

We dig up our share of shallow bases. It's always a nice bonus because it's a pain to pull them out or chip them off below grade.

Our standard is 24" diameter, 6' below and 2.5' above grade. About 1 yd of concrete.
Click to expand...

It was 18 feet not 18 inches. Easy to miss that!
 
cowboyjwc

cowboyjwc

Moderator
Staff member
Location
Simi Valley, CA
The highest pole we allow here is 25' measured from grade. Most are 14' and we still have about 4' in the ground and 2' above and they have to be engineered.
 
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