View Full Version : PVC boxes

Geoff K
07-28-2009, 09:13 AM
New to this forum. Please correct me if inappropriate. This message was posted on another forum but there appears to be little participation.

I'm planning on wiring the "back" side of my barn using PVC conduit. This is the end that is unheated and will have a few animals in it. This is in Wisconsin, temps from 100 F to -20F. I can not find the boxes and fixtures I need. (or I think I need) I've looked at 2 of the local big box stores and several on line supply sources. All the junction boxes are with one or two large openings only. Do I use those and drill holes in them for more conduits? Are there bushings to glue in to glue the conduit? I could not find any boxes to accept the light fixture. What do I use for that? I found 1 outlet box with only 1 conduit opening in it.

I need 4 large junction boxes, ranging from 24.75 ci to 38.25 ci. I need 9 boxes (round?) for mounting light fixtures, probably old style incandescent lights, and 6 switch/outlet boxes. The plan is a tree with a junction box at the beginning with 2 circuits coming in, a main run with branching lights and outlet runs, each branch point from a junction box. 2 of the junction boxes will have 4 conduits running from them and 2 will have 5. The sizes and info is taken from "Wiring Simplified" by Richter/Schwan/Hartwell.

Are the boxes treated differently in PVC use than in regular house wiring?

Where do I look for PVC boxes, etc.? Are they available?



07-28-2009, 09:33 AM
You could use metal boxes with ko's (knockouts) and lock nuts just like if you were running emt (metal conduit). You'll have to glue on threaded adapters in either 1/2'' or 3/4'' depending on which size you are running/

07-28-2009, 12:27 PM
4x4 metal square boxes come with 3 openings on each side. As for the "round" boxes, use the metal ones with an opening all four "sides".

Geoff K
07-28-2009, 03:01 PM
killavolt and hj, thanks for the info. Are you speaking of the same boxes I use in the shop/house? One of the risks in the barn is the bugs and debrit that collects in the box. It can cause shorts and fires. Thus I'd like boxes with no or minimal access for the little things in the barn. (I have arc fault interruptors in these circuits.) Also, if I'm already using metal boxes and have to ground them and use threaded connectors, would it not be just as easy to use metal conduit?

Thanks for your help.


07-28-2009, 05:44 PM
I would use conduit, but grounding the boxes is no big deal if you get the green pigtails with the screws already attached.

07-28-2009, 06:33 PM
You can still use pvc conduit but ground the boxes and devices with green wire pigtails as HJ has suggested.