Step 1 : Overview


This HowTo illustrates the basic steps to enclose a four channel SSR board in a weather resistant single gang blue box.

This design uses extension cords to connect the lights and the electronics sit on top of an 18 inch metal base made from 1/4 threaded rod that is simply stuck in the ground. The base helps to protect the electronics from problems caused by rain and snow; both are common to my area during the Christmas season.

This first picture shows a completed enclosure in front of a small maple tree. The diameter of the tree trunk is approximately 6 inches.

Warning: The wires and circuit contained inside the enclosure have 120 volts present. Contact with 120 volts can cause serious harm or even death. Use of any information contained in this HowTo is at your own risk. It s also your responsibility to satisfy local electrical safety codes and regulations.

Step 2 : Prepare the enclosure


The Carlon box show on the left has a few advantages over the inexpensive interior blue plastic boxes that one can often find for less than $.50. First there are no interior obstructions that are intended to secure wires or to mount plugs or switches. Second the sides are square and there are no angled recessed areas for the wiring. The square sides help to simplify the steps needed to make the box weather resistant. Lastly the box is a bit stronger due to the type of plastic used and a thicker wall construction. Unfortunately these advantages will cost you a bit more, around $1.40.

To prepare the boxes:

a. Cut off the outside mounting tabs and remove the nubs used for the face plate screws. The box on the left is before alterations and the one in the middle is after the changes.
b. Sand the sides relatively smooth. A belt sander works well if you have one.
c. Wrap the sides and bottom with water proof duct tape, as show on the box on the right. I used 2 inch black "Gorilla Tape" but there other manufactures who sell similar products. The tape that I used was only available in a two inch width. To cover the box required two strips of tape for the sides plus a piece for the top.

Step 3 : Circuit board considerations


My SSR design is a variation of the one described in Sean Bowf's HowTo so there will be some slight difference in the PCB size and component placement. The following information should help you determine if there are any changes needed to accomodate the SSR boards that you are using.

PCB size: 2.5 inches by 2.0 inches
Height: 1.5 inches from the bottom of the PCB to the top of the heat sink
RJ45 jack: centered along the 2.5 inch side with 1/4 inch overhang

Heat sinks: two pieces - 1/2 by 3/4 aluminum channel and aluminum U-channel that is described as "trim channel for 1/4 plywood" (from Value).

I use this approach for the heat sinks to allow for a good amount of thermal mass and surface material, and to keep a fairly low profile. The SSR's are squeezed between the two pieces of aluminum and held using #6 by 1/2 inch sheet metal screws.

Step 4 : Build the wooden base


Cut the base from 3/4 pine following the steps below:

A. Cut a rectangle from 3/4 pine with dimensions that match the external size of the blue box ( 3 1/8 by 2 1/4 inches).
B. Cut a 1/2 inch high groove on each side of the block. This recess is to allow the wood to fit inside the blue box. The 1/4 lip that remains will help create a lid.
C. Cut two blocks of wood 3/4 by 1/2 by 1 inch. Glue these blocks on the bottom left and right corners as show in the picture on the right, use water proof glue. The circuit board will eventually be screwed to these blocks.
D. Drill a 1 1/8 hole in the center of the block, 1/2 inch deep using a spade bit or fostner bit. Eventually a square will also be cut in this area to accept the RJ45 socket. This recess will help protect the CAT5 connection from the elements.
E. Drill a 3/8 hole through the block in the upper left and upper right of the block. These holes will be used for the four extension cords, two cords on each side. The location for these holes are not critical.
F. Drill a 1/4 inch hole through the block in top center of the block. This hold will be used for the power supply cable (plug). The location for this hole is not critical.
G. Drill a 1/4 inch hole 1 1/8 inch deep in the bottom left and bottom right of the block. These holes are drilled through the base and into but not through the blocks that were glued on in step C above. These two holes will be used for the metal stand. The holes are not drilled all the way though to keep the metal rods from contacting the electronics.
H. paint the bottom and edges of the wood to help protect the wood from the weather.

Step 5 : Mount the base and add wires


Hold the SSR circuit against the wooden blocks and mark the opening in the base that is needed for the RJ45 jack. Cut the opening using a chisel or drill a hole and file the hole square. Mount the PCB to the wooden blocks using two small wood screws, as seen in the picture.

Cut off the male plugs from the ends of three 6 foot extension cords and cut one 12 foot extension cord in half. Note: I like to use 6 foot cords because a local discount store sells them for $.79 each, although longer lengths would be handy at times.

Pass two of the cords with the female plugs through the left outside hole and tie an electricians knot in each cord to keep the wire from slipping through the hole. Repeat this for the hole on the right side. Pass the cord with the male plug through the center hole and tie a knot in this one as well.

Cut the wires to a length that allows each wire to be connected to the PCB without any strain on the wire or circuit board. Lightly tin the wires with solder and connect one wire from each cord to the proper PCB connector.

Trim the remaining five wires to a shorter length, tin, and twist them together using an electrical wire nut.