flat roof conduit stubby conduit connection methods

[JOHN MACKAY]

on a flat roof we have 1" to 3" lengths of 3/4" conduit sticking out. what do you recommend as a connection method to these stubs 1/60/208-230 20 amp . we are feeding small rooftop hvac units. we are trying to avoid the "wobbly" problem from an unsupported box. the actual question is "the wobbly" problem not the height. is there a bracket or box mount that solves both the short conduit junction and the "wobbly" problem
thanks.

 

[roger]

Use something like THESE with an "L" bracket and short lengths of strut.

Roger

 

[hbiss]

on a flat roof we have 1" to 3" lengths of 3/4" conduit sticking out. what do you recommend as a connection method to these stubs... we are feeding small rooftop hvac units. we are trying to avoid the "wobbly" problem from an unsupported box. the actual question is "the wobbly" problem not the height. is there a bracket or box mount that solves both the short conduit junction and the "wobbly" problem

Lots of problems here.

If the roof penetration was done properly by a roofer using pitch pockets the stub up wouldn't be wobbly. Nothing you are going to do about it yourself. Get a roofer.

Your other problem is attaching a box to the conduit. Your hvac units require a disconnect, normally that would be mounted to the unit. You would run sealtite from the stub up to the disconnect. No box on the stub up because you can't use the conduit to support it.

-Hal

 

[JOHN MACKAY]

thanks for input, additional question--- is an antenna tripod mount with conduit centered in mast hole acceptable stabilizer under nec

 

[Chamuit]

LB?
3-hole deep bell box, if you need more space. Horizontal run can come in the back.
If you are going in different directions, a 5-hole 2-gang with the side holes can be useful.

 

[hbiss]

thanks for input, additional question--- is an antenna tripod mount with conduit centered in mast hole acceptable stabilizer under nec

Absolutely not. The conduit should be fastened to the structure from below the roof inside. The penetration is sealed with a pitch pocket or equal. You can transition from the conduit to the sealtite with an LB but you cannot put a box on the conduit.

It's like I'm trying to tell you, this isn't your problem as the HVAC guy.

-Hal

 

[roger]

It's like I'm trying to tell you, this isn't your problem as the HVAC guy.

-Hal

You haven't looked at the OP's profile have you?

Roger

 

[hbiss]

You haven't looked at the OP's profile have you?

Roger

Ok, now I did. But it doesn't change my answer.

-Hal

 

[Eddie702]

The conduit should be supported under the roof. I see no reason you couldn't put an LB on it the put roof blocks under the outlet pipe coming from the LB

 

[JOHN MACKAY]

lb is a good idea, but splicing the wiring inside an lb would be better done in a disconnect or junction box, and that's when the "wobble" happens. a rock solid conduit won't eliminate the lack of support for the box. and that's the real problem, thanks

 

[sameguy]

Pipe to sealtite to the disconnect box, not seeing the problem here.

 

[hbiss]

Pipe to sealtite to the disconnect box, not seeing the problem here.

The problem is that the conduit isn't supported properly before it goes through the roof. I'm surprised the penetration doesn't leak. There is no way you are going to fix somebody else's crap work from outside. Go inside and see what the problem is.

-Hal

 

[JOHN MACKAY]

sameguy, so.... conduit, to L box ,wire nut to sealtite whip, to rtu mounted disconnect, to connection, either direct rear access or additional whip to rtu electrical access point? thanks

 

[JOHN MACKAY]

i was not aware i suggested the conduit was not supported at the roof or below, my intention was to have a secure junction above the roof line. where disconnect knock-outs or aluminum fittings to aluminum boxes, might be easily damaged by tripping over them. the L box idea seems best - commonly done, and has sturdy connections while not being load loaded in a single plane. thanks

 

[hbiss]

lb is a good idea, but splicing the wiring inside an lb would be better done in a disconnect or junction box, and that's when the "wobble" happens. a rock solid conduit won't eliminate the lack of support for the box. and that's the real problem,

Now from reading this I have to ask- is the stub-up wobbling in the hole where it comes through the roof? Or are you talking about a box or disconnect sitting on the stub-up wobbling?

As I've said, you can't put a box or disconnect on the stub-up. Either has to be independently supported. The way to do that is to build a frame out of Unistrut or Kindorf, the bottom of which is attached to the roof. Or mount the disconnect to the A/C unit.

sameguy, so.... conduit, to L box ,wire nut to sealtite whip, to rtu mounted disconnect, to connection, either direct rear access or additional whip to rtu electrical access point? thanks

Yes, except that you can't splice in the LB. So that means rerunning the THHN so that you will have sufficient length to make it from the LB through the Sealtite to the disconnect.

-Hal

 

[JOHN MACKAY]

yes, you got it.... i have 16 of these to do.....2 or 3 would be difficult / improbable to pull new wire ...hence the splice problem. any ideas on that problem? thanks

 

[JOHN MACKAY]

let's start fresh.... a rock solid 1/2" conduit stub about 3" tall with 6" of slack wire sticking out of a flat roof with "mushroom top" weatherizing / stabilizing roof accessory.
connection to disconnect is unreliable because disconnect box connection is sheet metal and easily damaged by tripping over
aluminum box is tougher but still not unbreakable
best solution would be a steel box with height adjustable feet or foot brackets - allowing support from roof, while allowing splicing new length of conductor forward to disconnect, whip, whatever is needed (read required) to terminate at rtu
is there such a product? (brand, name part # ) thanks john m

 

[hbiss]

What's a "mushroom top weatherizing / stabilizing roof accessory"??

-Hal

 

[hbiss]

best solution would be a steel box with height adjustable feet or foot brackets - allowing support from roof, while allowing splicing

Nobody makes anything specifically for that but you can get there. Unistrut is your friend. Take a look at #P1498 or P1499 on page 83.

1603_GEC Cover

-Hal

 

[sameguy]

Go under cut a box in, pull the ~10' in.