installing outdoor outlet box directly behind electrical sub-panel knockout

[remagenman]

I want to install a outlet box on the exterior wall of my sub panel box, meaning the sub-panel is mounted about 5 feet, next to main panel on my garage wall, next to door. I have a planer and some other 110v power tools that sit right outside my garage and usually run an extension cord from directly inside my door to run these.

The best location for the outlet, because I already installed exterior 220v outlets for welder, etc., would be directly behind sub-panel back bottom knockout, directly facing my exterior wall its mounted on. So it would be = sub-panel, wall sheathing, outlet box. The wall/sheathing is a 1/2 inch thick.

Problem I'm facing is what connector can I use to transition from outlet box 1/2 screw hole through wood and into metal sub-panel box?

Is this even allowed?

ps, sub-panel knockout and outlet directly behind it would be mounted 5 feet up from ground level.

Thanks.

 

[Terry D]

Yes this is allowed. You would just use a 1/2 or 3/4 metal threaded ******. They come in different lengths starting with a close ****** on up. If is about 2 1/2 inches or more you could also use a couple of pvc box connectors and glue them on a short peice of pvc. You can use a piece 1 inch, then you would just have the thickness of the 2 connectors

How i do it is use a long 1/4 inch drill bit. Drill from the inside out before you remove the knockout. Drill all the way to the outside. Then with that hole in the knockout, you can use a small screwdriver to pop it out. Then drill from the outside in with a hole saw using the pilot hole. If you use the pvc way, you with have to use a larger hole saw than the knockout because the fittings are larger than a threaded ******

 

[remagenman]

Yes this is allowed. You would just use a 1/2 or 3/4 metal threaded ******. They come in different lengths starting with a close ****** on up. If is about 2 1/2 inches or more you could also use a couple of pvc box connectors and glue them on a short peice of pvc. You can use a piece 1 inch, then you would just have the thickness of the 2 connectors.

Just got back from my local Habitat for Humanity store and they had exactly that, a 2 inch long 1/2 inch threaded ******, fits in the outlet box and through the panel, 25 cents! Only thing is that in my haste to make this work last night I knocked out the 3/4 inch ring after trying the 1/2 inch knockout first. Now I need a 3/4 to 1/2 inch connector or leaving it as it and sealing the hole with caulk. (edit, just saw that they sell reducing washers for this purpose).

My thinking is the box will be secured on the outside. (Damn, now I have the additional problem of drilling through the wood and into the metal if I use too long a screw!).

 

[sparky 1971]

Just got back from my local Habitat for Humanity store and they had exactly that, a 2 inch long 1/2 inch threaded ******, fits in the outlet box and through the panel, 25 cents! Only thing is that in my haste to make this work last night I knocked out the 3/4 inch ring after trying the 1/2 inch knockout first. Now I need a 3/4 to 1/2 inch connector or leaving it as it and sealing the hole with caulk. (edit, just saw that they sell reducing washers for this purpose).

My thinking is the box will be secured on the outside. (Damn, now I have the additional problem of drilling through the wood and into the metal if I use too long a screw!).

Or get a box with a 3/4" ko.

 

[justsam]

Are both the sub panel and the proposed receptacle box surface mounted?

 

[remagenman]

Are both the sub panel and the proposed receptacle box surface mounted?

No recessed into the 2x4 studs with a drywall cutout.

Made it work though and already used for some outside sanding. I installed the breaker and connected to a live panel since I have way too much wifi/ethernet connected devices to have to reset everything.

It's amazing what you can learn on youtube/google nowadays. Thanks for the input.