John Drake Services, Inc.
1427 E. 68th Street
Long Beach, CA 90805
electricity from the sun by John Drake II | home
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Many people run into a road block when it comes to passing wire or cable into a photovolatic module
or raintite box outdoors.
To me, the easiest way to do this is to use a raintite strain relief fitting.
The following are pictures and installations showing them.
Above is an assembled 1/2" (fits into a 1/2" pipe hole [7/8"]) watertite strain relief fitting, they
are also available in 3/4" size.
As you can see, it consists of the body (threaded on each end), a yellow washer (which goes on the
outside of the connection to seal it, a metal washer/nut with knobs (which goes on the inside of the box)
and in this case, three different compression glands.
Most strain reliefs only come with one compression gland with a round center.
The body is tapered inside to force the fingers on the end of the gland to compress when the cap is
The outside cap has flats on it, you would think these are for use with a wrench - THEY ARE NOT,
always tighten the cap by hand.
The plastic threads are easily stripped, and I did not read that somewhere, I have done it.
This connection provide two functions.
First, it seals out moisture, secondly it locks the cable in place so that if the cable is tugged on it will
not allow it to break the connections inside the box or wall.
Here is one mounted in the "J" (junction) box on the back of a photovoltiac module:
The following fittings are on the back of a plastic garden tool box holding a 48 volt battery bank:
The two large cables are the positive and negative power cables, the smaller one is a four conductor
cable for a Bogart Engineering TriMetric battery system monitor.