concrete ceiling and ceiing boxes

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Greg1707

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Alexandria, VA
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Business owner Electrical contractor
I will be installing ceiling fans and light fixtures from a concrete ceiling. The ceiling will be covered using 1.5" lumber and drywall. All of the boxes I have seen are 1.5" deep. How do I reach the 2" depth I need to be flush with the drywall?

Also I will be running NM cable parallel to the lumber. Is there a strap available to screw to the lumber to support the cables?
 

ActionDave

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Durango, CO, 10 h 20 min from the winged horses.
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Licensed Electrician
I will be installing ceiling fans and light fixtures from a concrete ceiling. The ceiling will be covered using 1.5" lumber and drywall. All of the boxes I have seen are 1.5" deep. How do I reach the 2" depth I need to be flush with the drywall?
Scraps of .5" plywood behind the box.

Also I will be running NM cable parallel to the lumber. Is there a strap available to screw to the lumber to support the cables?
Zip ties with an eyelet on the end is what I have used. Best to anchor them in the concrete 1.25 or even 1.5 inches away from the furring strips to stay in line with 300.4.
 

69gp

Senior Member
Location
MA
I will be installing ceiling fans and light fixtures from a concrete ceiling. The ceiling will be covered using 1.5" lumber and drywall. All of the boxes I have seen are 1.5" deep. How do I reach the 2" depth I need to be flush with the drywall?

Also I will be running NM cable parallel to the lumber. Is there a strap available to screw to the lumber to support the cables?

use 1/20 or 3/8 threaded rod and anchors. Set the box to the depth you need with washers and your all set
 

Fulthrotl

~Autocorrect is My Worst Enema.~
I will be installing ceiling fans and light fixtures from a concrete ceiling. The ceiling will be covered using 1.5" lumber and drywall. All of the boxes I have seen are 1.5" deep. How do I reach the 2" depth I need to be flush with the drywall?

Also I will be running NM cable parallel to the lumber. Is there a strap available to screw to the lumber to support the cables?

assuming the ceiling is furred with 2x4's laid flat...

4s box shot to ceiling. as it's load bearing, i'd hammer drill it, and
use red head anchors....
1/2" 3O ring gives you flush with finished drywall.
as for the NM, you could staple it to the side of the 2x4,
but then it is a good candidate for drywall screws hitting it.

i'd shoot a ceiling wire clip to the concrete, and ty wrap the NM to it.
 

infinity

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Location
New Jersey
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Journeyman Electrician
Best to anchor them in the concrete 1.25 or even 1.5 inches away from the furring strips to stay in line with 300.4.


I agree, 300.4 would prohibit any attachment to the ceiling framing members unless you only occupy a 1/4" of wood space against the concrete.
 

Fulthrotl

~Autocorrect is My Worst Enema.~
Good plan for standard fixtures, but OP is also installing ceiling fans. I think the rings would not work then.

duh. correct, of course.

the round fan rated box wins for me then...
put it up with two 1/4"-20 redheads, and with
any luck, you can hit a post tension cable in the
concrete, and have big fun!

always the optimist, i am.... :lol:
 

Greg1707

Senior Member
Location
Alexandria, VA
Occupation
Business owner Electrical contractor
plastic extension rings

plastic extension rings

Is there such thing as a plastic extension ring for ceiling boxes? There are several products available for wall boxes. I have had situations where a contractor installed an additional layer of drywall over the existing. Of course this leave the boxes recessed.

For new work I have used 1900 boxes with a round mud ring. I have had problems with this when installing the fixtures. The rings are 3" and the mounting brackets are designed for 4".

To support cables across a concrete ceiling furred out with 1.5 lumber, I have used long screws. I attached the 3.5" screw to the edge of the lumber. The screw supports the cables and are secured with zip ties.
 

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
To support NM or other cable from concrete I have shot 1/2" EMT strap and ziptied cable to it.
 

augie47

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Location
Tennessee
Occupation
State Electrical Inspector (Retired)
I agree, 300.4 would prohibit any attachment to the ceiling framing members unless you only occupy a 1/4" of wood space against the concrete.

3M Furring strip cable stak-its will give you the required distance.
 
I will be installing ceiling fans and light fixtures from a concrete ceiling. The ceiling will be covered using 1.5" lumber and drywall. All of the boxes I have seen are 1.5" deep. How do I reach the 2" depth I need to be flush with the drywall?

Also I will be running NM cable parallel to the lumber. Is there a strap available to screw to the lumber to support the cables?

One hole strap for NM cable. Strap.jpg
 
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