Drilling into deck

mstrlucky74

Senior Member
Location
NJ
Here's the situation. Have trapeze mount a transformer in an electrical room where conduits, duct, panels are already installed. When I was in the electrical closet there's about 7' from the conduits to the slab above. It's very congested. How would you drill the slab if you could only get the drill to about 7' away from the slab? not a 7' bit...lol..without removing the conduits? Thanks
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Here's the situation. Have trapeze mount a transformer in an electrical room where conduits, duct, panels are already installed. When I was in the electrical closet there's about 7' from the conduits to the slab above. It's very congested. How would you drill the slab if you could only get the drill to about 7' away from the slab? not a 7' bit...lol..without removing the conduits? Thanks
If you can't get up there with a drill, how the heck are you going to mount the transformer????
 

GoldDigger

Moderator
Staff member
If you can't get up there with a drill, how the heck are you going to mount the transformer????
Suspended below all the garbage on trapeze(s)?
How to set the anchor into the concrete at that distance is a valid question.

Drill through the slab from above and puts nuts in recessed holes in the top of the slab?
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
get the anchors in deck and drop rod below all the garbage. But how the hell are you gonna set the anchors.
Ahhh, I see your intent. How about powder actuated cartridges? Hilti makes a broad selection. The only caveat is sometimes job specs forbid them.
 

Fulthrotl

~~Please excuse the mess. Sig under construction~~
Here's the situation. Have trapeze mount a transformer in an electrical room where conduits, duct, panels are already installed. When I was in the electrical closet there's about 7' from the conduits to the slab above. It's very congested. How would you drill the slab if you could only get the drill to about 7' away from the slab? not a 7' bit...lol..without removing the conduits? Thanks
how heavy a transformer? 112kva?
slab post tension?
robertson decking?
structural steel you can hang off of?
seismic support?

and a design with a structural engineers wet ink signature on it?

i've shot strut to the deck with a couple 10' long pieces of
solid back strut, with a hilti gun with a strut nose on it.
use 3/8" pins. lots of them. then drop rod from the strut, and hang
the xfmr.

there is almost always a place where i can wiggle thru a layer
of conduit. work some 6' pieces of 2x12 planking up thru the
layer, and stand on them. the concrete should be an easy reach.

if the floor above isn't finished, lay out where you want the rods
dropped,and drill a 1/2" hole all the way thru, blowing out the
floor.

then go up on top and counterbore the holes with a 1 1/2' bit.
go down 3". put a rod coupling and three 1/2" x 1 1/2" washers
on 10' of running thread, and drop them down in the counterbored holes.

fill the holes up with hilti structural grout.
 

ActionDave

Moderator
Staff member
Location
Durango, CO, 10 h 20 min without traffic from wing
Occupation
wire pulling grunt
how heavy a transformer? 112kva?
slab post tension?
robertson decking?
structural steel you can hang off of?
seismic support?

and a design with a structural engineers wet ink signature on it?

i've shot strut to the deck with a couple 10' long pieces of
solid back strut, with a hilti gun with a strut nose on it.
use 3/8" pins. lots of them. then drop rod from the strut, and hang
the xfmr.

there is almost always a place where i can wiggle thru a layer
of conduit. work some 6' pieces of 2x12 planking up thru the
layer, and stand on them. the concrete should be an easy reach.

if the floor above isn't finished, lay out where you want the rods
dropped,and drill a 1/2" hole all the way thru, blowing out the
floor.

then go up on top and counterbore the holes with a 1 1/2' bit.
go down 3". put a rod coupling and three 1/2" x 1 1/2" washers
on 10' of running thread, and drop them down in the counterbored holes.

fill the holes up with hilti structural grout.
Sure, that's what I would do, that's what you would do, what the op wants to know is how do you do this with a monitor, mouse, keyboard, and sticky notes and not loose out on a bonus.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
How wide is the room and what are the walls made of? You could possibly run strut from wall to wall below everything else and hang the transformer from the strut.
 

mstrlucky74

Senior Member
Location
NJ
how heavy a transformer? 112kva?
slab post tension?
robertson decking?
structural steel you can hang off of?
seismic support?

and a design with a structural engineers wet ink signature on it?

i've shot strut to the deck with a couple 10' long pieces of
solid back strut, with a hilti gun with a strut nose on it.
use 3/8" pins. lots of them. then drop rod from the strut, and hang
the xfmr.

there is almost always a place where i can wiggle thru a layer
of conduit. work some 6' pieces of 2x12 planking up thru the
layer, and stand on them. the concrete should be an easy reach.

if the floor above isn't finished, lay out where you want the rods
dropped,and drill a 1/2" hole all the way thru, blowing out the
floor.

then go up on top and counterbore the holes with a 1 1/2' bit.
go down 3". put a rod coupling and three 1/2" x 1 1/2" washers
on 10' of running thread, and drop them down in the counterbored holes.

fill the holes up with hilti structural grout.
wow impressive. Thanks
 

mstrlucky74

Senior Member
Location
NJ
How wide is the room and what are the walls made of? You could possibly run strut from wall to wall below everything else and hang the transformer from the strut.
About 8'. That's a good thought. Just have to make sure that span could support xfrmr.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
About 8'. That's a good thought. Just have to make sure that span could support xfrmr.
If you use 3" Unistrut I doubt you'd have a problem. Their manual says with a span of 8 ft the maximum uniform load is 1,310 lb. The transformer will be more like a point load, and it makes a difference if it's near one end or in the middle, so you'd have to go to the manual and do some calculations.
 
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