Thursday, April 23, 2009

Skin Shredders - Things that cut you in the dark.

Junction boxes, like the one shown above, abound in theatres. Unless there is some structural problem with embedding the box flush in the wall, surface mounted boxes should not go into new construction. However, when they are installed, the contractor that provides the cover plate should see that it is fabricated with a cover plate that matches the face dimension of the back-box.

Retrofit Recommendations:
  • If possible, have an electrician remove the plate and take it to a metal shop to have the excess metal sheared-off and the edges ground smooth.
  • Replace the plate with a new on that is properly sized (and some good labelling would be nice, too!) Custom plate fabrication is not very expensive. Draw what you want and dimension it, including the mounting screw holes and engraving, and get a quote. Now is a good time to add connectors, relable circuit numbers, and even change the color of the plate. Black may be good for the upstage wall, but for just about everywhere else that the audience can't see, white is much easier to find and read in the dark, particularly in floor pockets.
  • If the plate can't be modified or replaced, then install hardwood blocking around the box so that the perimeter of the wood framing is slightly larger than the exposed metal cover plate. Routing a recess in the face of the hardwood frame to make the face of the plate flush to the face of the wood perimeter is also recommended. Note: Don't drive screws into the box sides, as they can pierce the insulation on the wiring within the box. With the power disconnected, install the screws into the wood from inside the box.

Another place that frequently has surface-mounted back-boxes are catwalks. These may be single or multi-gang back-boxes that were designed for flush mounting but were installed along an open railing. The standard sized gang cover plates that are then installed for DMX, Microphone, and Intercom receptacles, or light switch cover plates, are over-sized and leave sharp corners exposed to snag and cut.

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