Conduit in a footing
- Thread starter tortuga
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
As long as the engineer's drawings show it that way, I can't think of any reason it can't be done. Not sure what it gains one though.
Its a change of panel location and they dont want to dig the gravel up and mess with the rebar.
Its not on the engineers drawings its residential single single story construction.
- Location
- Illinois
- Occupation
- retired electrician
The footing design needs to be evaluated to make sure it can still support the building with the conduit taking the place of part of the concrete.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
presumably the engineer that made the drawings considered this.
Its not an engineered foundation its a residential code 'prescriptive' design.
Its not a big deal I am trying to keep the feeder conduit considered 'outside the building'
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
Presumably there were than a bunch of engineers who reviewed it and found it acceptable.
I think the builder draws his own plans, no sign of a architect or engineer
- Location
- Illinois
- Occupation
- retired electrician
But I doubt that the prescriptive design accounted for the conduit in the footing, so it needs to be evaluated to a performance standard.
acin
Senior Member
- Location
- pacific grove california
- Occupation
- general building contractor est.1984 . C 10 elec. lic.as of 8 / 7/ 2020
Conduit probly needs to wrapped with plumbing foam tape
I definitely wouldn’t approve a footing like that.(as if someone would ask my opinion..)
However under the footing as long as you have required footing dimensions wouldn’t (shouldn’t) be a problem.
Monolithic slabs have many conduits in the footings..
Just make sure to have the required footing thickness.
ptonsparky
Tom
- Occupation
- EC - retired
PVC raceway would solve that issue.
Even though it is residential, when you're talking about the footing, I would ask for a structural engineers opinion at the least. If for no other reason than to save your ass instead of saying "it was on the drawing so I did it."
hbiss
EC, Westchester, New York NEC: 2014
- Location
- Hawthorne, New York NEC: 2014
- Occupation
- EC
It looks like @tortuga indicated them in the drawings. As far as doing that, I don't know but I don't like it. What gravel and rebar? Footings are always poured first. Why can't you locate your conduit under the floor slab? Are you saying they have the slab gravel and rebar placed before the footings are poured? Another point is when was the panel location changed, after the concrete prep was done? If so, seems to me it should be on them and not just say "I don't want to dig the gravel up and mess with the rebar".
-Hal
brantmacga
Señor Member
- Location
- Georgia
- Occupation
- Former Child
I know in many project drawings I’ve worked with, there is an alternate footing detail to be used if conduit will be placed there. We have to coordinate with the GC if we plan on having conduit in any footing. I avoid it unless absolutely necessary.
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drcampbell
Senior Member
- Location
- The Motor City, Michigan USA
- Occupation
- Registered Professional Engineer
Is this new construction or existing? Plastic conduit or steel? Are there any seismic criteria?
As depicted, with minimal rebar and a 2-inch and a 4-inch (?) conduit in an 8-inch (?) thick footer, running the length of the footer, would seriously weaken it if they were plastic. But I can't think of a good reason to run the conduit the length of the footer. Fasten it to the walls for the lengthwise portion and cross or penetrate the footer or basement wall at right angles, assuring that there's a minimum of 2 inches of concrete covering the rebar.
Over time, I'd expect to see something like this:
As depicted, with minimal rebar and a 2-inch and a 4-inch (?) conduit in an 8-inch (?) thick footer, running the length of the footer, would seriously weaken it if they were plastic. But I can't think of a good reason to run the conduit the length of the footer. Fasten it to the walls for the lengthwise portion and cross or penetrate the footer or basement wall at right angles, assuring that there's a minimum of 2 inches of concrete covering the rebar.
Over time, I'd expect to see something like this:
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
From a mechanical perspective, I doubt that a relatively small conduit, centered in the cross-section, would weaken a footing very much. I think the stresses are concentrated along the upper and lower surfaces.
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