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I have a project with a Raspberry Pi in a small enclosure that is in a weather-protected outdoor location. I currently have power and gpio signal cables entering the enclosure through grommeted holes, but need to add an Ethernet cable. It will be connecting to an Ethernet over powerline adaptor, so it will not be required to support high data speeds.

I'm looking at a couple possible approaches:

  • purchase a crimper, cut the end off a patch cable and install a new end after passing through a grommet. Advantage: neatest installation; disadvantage: purchase a tool that I may not need again.
  • cut the end off a patch cable and install an RJ45 jack, cram a short (6") patch cable into the enclosure. Advantage: no new tools needed (I have a punchdown tool); disadvantage: may be tough to cram the patch cable into the box
  • cut a cable and solder it back together after passing through the grommet. Advantage: no new tools; disadvantage: small wires tedious to solder.
  • Mechanical: cut a slot from the edge of the enclosure, slit the grommet and slide it and cable into the slot, then glue a patch to close off the slot. Disadvantage: messy install

Am I missing anything else? I originally considered soldering directly to the PCB, but the Pi uses a mag jack.

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    \$\begingroup\$ While more expensive, there are water-tight RJ45 connection systems. \$\endgroup\$
    – kenny
    Commented Aug 31, 2014 at 1:24
  • \$\begingroup\$ @kenny that would be a great answer. I see a couple candidates that might work out for me. \$\endgroup\$
    – TomG
    Commented Aug 31, 2014 at 1:53
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    \$\begingroup\$ RJ45 crimpers are almost free, but I like @kenny's approach. \$\endgroup\$
    – Spehro 'speff' Pefhany
    Commented Aug 31, 2014 at 2:14
  • \$\begingroup\$ Which enclosure do you have? \$\endgroup\$
    – Funkyguy
    Commented Aug 31, 2014 at 3:23
  • \$\begingroup\$ @funkyguy - it's a small project box from Radio Shack, with Tyvek tape over the seam from the cover. I used a dremel to grind off some of the internal ribs to create a bit more space. \$\endgroup\$
    – TomG
    Commented Aug 31, 2014 at 16:15

2 Answers 2

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Use cable gland, they are for cheap and water-proof (IP54 to IP67). Try PG11 (5-11 mm dia in), with or without a little forcing/hack (depended on concrete manufacturer/model), it is possible to trace an RJ45 pre-terminated UTP cable inside the enclosure. Mounting a PG onto a box is simple: only round hole is needed. Drill it on a free surface of a box side and install the PG.

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    \$\begingroup\$ For future reference, the trick with this solution is to find a gland that has an opening in the housing large enough for the RJ-45 jack to pass through, while also having a grommet small enough to fit the cable. The grommet will stretch around the jack, but the housing will not. :P \$\endgroup\$
    – PKL
    Commented Jul 9, 2015 at 20:33
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purchase a crimper, cut the end off a patch cable and install a new end after passing through a grommet. Advantage: neatest installation; disadvantage: purchase a tool that I may not need again.

If you go down this road make sure you buy the right connectors. Connectors designed for solid core wire won't make reliable connection on stranded and vice-versa.

cut the end off a patch cable and install an RJ45 jack, cram a short (6") patch cable into the enclosure. Advantage: no new tools needed (I have a punchdown tool); disadvantage: may be tough to cram the patch cable into the box

This is poor from a reliability perspective. Commercial patch cables are nearly always made with stranded core cable. Punchdowns are designed for solid core cable and are likely to make a poor connection with stranded.

cut a cable and solder it back together after passing through the grommet. Advantage: no new tools; disadvantage: small wires tedious to solder.

This will work fine as long as you keep the join reasonablly short.

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