I am trying to install a simple surface mounted junction box, in terms of the Code it seems pretty straightforward, but have run into several practical problems. Thought I might as well ask more experienced people here how they would solve the issue.
I have 3 8AWG solid wires and a bare ground in a recessed 1-gang metal box at a covered patio stucco wall (see Pic 1). Those are connected to a double 60 Amp breaker at the main. Now, I would like to splice those to extend them just a few feet to a subpanel (which cannot be mounted in the current low position, behind an AC unit).
I got some huge wire nuts (see pic 2) and because of the number of large wires and connectors I will need a deep box (e.g pic 3). Ideally I would have a deep extension box, but cannot find those. Also a minimum 3/4in (likely Liquidtight) conduit going to the subpanel.
Here are the problems:
- the existing box is a bit proud of the wall, which makes the standard surface box difficult to mount and insulate. Sigma boxes I referred to above come with two tiny flat mounts. I could add some spacers, and cut foam for makeshift insulation?
- The wires are quite short, adding a box with a single hole in the back leaves me with only about 1.5" of wire to work with. ideally I could use the existing wall box and the new addition as a single unit
So, any other types of box that would mount better over the existing setup? Should I create a small wooden frame for mounting and insulation? Are there any code challenges?
Best Answer
The problem I see is your wire fill with 4 ea #8 wires counted at 3 cubic inches each you are at 12 without a clamp. I would probably be looking at a double gang bell box. One thing that regularly has to be done in industrial facilities is modifications to boxes or gutters. I would verify your local AHJ will allow this on residential. I would cut the back of a bell box out to slide over the existing device box and mount it directly to the wall this will look better and provide the additional space to splice the wires. Since the existing box is proud of the wall a bead of calking across the top or even around that box prior to sliding it over the existing box would make it waterproof. I have done this with both boxes and gutters coming out of concrete walls and steel plate. Your stucco would be the same as a concrete wall.
Trying to splice heavy wires in two tight a space is how wires get the insulation damaged and end up shorting out on the box or they vibrate through at a later date.