Homemade switched outlet strip

Posted by Chris on September 13th, 2010 filed in Hacks

Before I moved into an apartment in the city, I had a house with a giant corner desk in the corner of my bedroom.  This was back before LCD screens, so it had three *giant* CRT monitors which sucked a fair amount of power, even when off.  That, coupled with other things that had no need to stay on all the time (ahem, always powered subwoofer speaker) made me want an easier way to turn them off to save energy.  Leaving digitallyimported on all day, every day, probably didn’t help too much either.  A little romex, some plastic outlet boxes (and outlets), a plug, and a couple of light switches and I had a solution.  I left it along with the desk when I moved, and have wanted another one ever since.  It is very straightforward – just like powering a lamp, except instead of a light bulb at the end, it’s a series of outlets.

Please check the update at the end – I used the wrong clamps.

Materials

Consumables

  • 1 plug (I get two because I almost always mess up the first one)
  • 1 light switch
  • 1 light switch plate
  • 1 box for switch
  • 2 wire nuts (yellow)
  • Romex/nm cable – length up to you.  I used approx 15 feet

For each outlet:

  • 1 box
  • 1 outlet
  • 1 cover
  • Romex to length

Consumables

Tools I used:

  • Screwdriver (screwgun for laziness)
  • Snips
  • Wire Stripper
  • Utility Knife
  • Electric multi-tool (continuity tester)
  • Needlenose Pliers
Outlet strip tools used

Tools used

Attaching the plug

Decide how long you want the “tail” to be – that’s the part going between the switch and the wall – and add a foot for good measure.  Strip about 3-4″ of the outer shield off, and get rid of the paper around the bare copper wire.  Push the bundle through the plug end.  Strip about 1/2″ off the other two wires.  The only tricky part is getting the end right – Black is the “hot” wire, and is on the right as you face an outlet.  It also always has brass (colored) screws.  I always use needlenose to create the loop in the end of the wire before screwing it in. After that, it’s just left to re-attach the plug cover.

Wires connectedreconnected

Creating the outlet strand

I start at the end of the line.  Take one of the metal boxen, and knock one of the circles out on the end – this is the only one that will have only one open hole.  Hopefully you’re using some sort of wire protectors – I got the wrong ones apparently… oops.  I’ll be re-doing this with the correct ones, by the way.  I put about a foot in between the boxes, so cut off a 18-20″ length of romex and stripped it as before.  It’s easier to put into the outlet box if you put the hook on the end after inserting.  Outlets are the same as the plug, but there’s another hint with them – the shiny copper is the hot (black) side.  Don’t foget the ground (bare copper) goes to the green screw.  After that, simply mount the outlet in the box.  Don’t forget to tighten down the protective clamp. I wait to put the covers on until I’m sure I haven’t messed it up.  Testing as I go makes that even less of a problem.

After the first one, it is a very simple manner of doing the same thing for however many boxes you have.  Basic procedure:

  1. Knock out end(s)
  2. Add protection
  3. Cut wire to length, plus 6-8″
  4. Strip outer cover off romex
  5. Get rid of paper around ground wire
  6. Strip the black and white wires
  7. Insert wire into box
  8. Make the bends in the three wires
  9. Attach to hot side, cold side, and ground
  10. Repeat for other end going out the other side of the box, and to the other side of the outlet block (excepting the ground)
  11. Mount outlet
  12. Tighten protective clamps (Get the right ones)
  13. Test for continuity where it should be (and where it shouldn’t)
  14. Put covers on

Knockout box with steel connector

Outlet partly wired, in the series

A finished box in the series.

Connecting the switch

In this case, I knew where I wanted to mount my switch, and wanted both wires to come out of the back.  (Another advantage of the metal knock-boxes, by the way).  It’s actually hard to find single pole switches anymore, but not a big deal.  The switch will be marked “up”, and on there back there will be a pole that is differently colored.  That’s the “hot” or “common” one to connect to the outlet.  That one will always have live electricity going to it, no matter how the switch is oriented!   I’m lazy, so I used the continuity tester to see which of the other poles would be “on” when the switch was on.  The black wire from the wall cord goes to the always hot pole, and the black from the outlet strip goes to the one you just found that’s switched how you want it.  The two white wires and the two bare wires get connected via the wire nut (or grounding screw on the switch).

Switch wired up. (Only black goes to the switch)

Testing

Connect one lead of your tester to the cold pole of the plug (left as it faces the wall).  First, check there is no connection to either of the other two prongs on the plug.  Then,  going down the line, check that the meter says it’s connected to the cold half of the outlet at all of the outlets (you can just do one per pair, they’re connected within the block).  Going back down the line check that the meter says it is *not* connected to any of the hot sides or the grounding plugs.  Switch to the hot pole on the plug and leave the switch off.  It shouldn’t read as connected to anything down the line of plugs now.  Turn the switch On, and make sure it’s only connected to the hot plugs, and that the prongs still don’t read that they are connected.  If any of those steps go awry, there’s something somewhere it shouldn’t be…  I check once in a while as I go just so I don’t get confused – I just leave one lead in one side of the outlet at the end and check after I finish a plug.

Checking everything for continuity

Finishing up

If you haven’t already put the covers on, now would be a good time.  I plan to mount this facing up on the square steel going horizontally across my desk back so I attached some reasonably strong hook and loop fasteners to the back of each box.  The switch goes in the front of the desk in the upper right corner where it’s easy for me to switch on and off as I come and go, so I put it on the top and right.  To make it easy – “measure twice, cut once.  or better yet, don’t measure at all” – I put the other half of the hook and loop combo on the back of each box and just pressed it into place rather than trying to match up.  It’s held up for a while now with absolutely no worries.  Plug it into the wall (or a power strip), and plug something cheap into one of the plugs ( I used a monitor… ahem ) and flip the switch.  Done!

Updates, because I messed up:

  • Get the right clamps!  The wrong ones will either run a screw into the wire or end up fraying it causing a dangerous situation.  I have the wrong ones in these pictures.  I got done taking pictures and re-did the entire strip with the correct (safe) ones.
  • This is not for moving around at all.  Solid wire shouldn’t be moved/bent.  The only reason I’m comfortable using this is because it’s close to a permanant install.
  • Plug it into a real power strip.
  • There’s really not many reasons to do something like this instead of a good power strip.

A couple of references:

How to wire a household outlet

Wiring a 3-way switch

Using a multimeter

How to wire a plug (part of a hackaday article)


9 Responses to “Homemade switched outlet strip”

  1. Jeff Says:

    I’m an electrician, and the first thing that jumps out at me in the photos is that you’ve used the wrong “protective clamps” for securing/protecting the romex as it enters the device boxes. This creates an unsafe situation whereby the connector’s screw can wear on the cable’s insulation, eventually creating conditions for a fault.

    The connectors you’ve used are designed to be used with 3/8″ metal-clad (MC) cable. There are several different types of box connectors for NM cable. You’ll want to edit your post with the correct parts, or with a disclaimer at the beginning, noting that you’ve used parts that could be dangerous.

  2. Walt Says:

    This is a fire hazard unless you include a circuit breaker in it, or plug in into a real outlet strip.

  3. Marshall Says:

    Great idea.
    An observation for safety – you used clamps designed for conduit. The screw can penetrate the romex/insulation and cause a short. This will happen sooner if your setup is moved frequently. Please replace the clamps with those designed for romex.
    Take care,
    Marshall

  4. Henry Says:

    Everything about this build is a bad idea

  5. Homemade power strip - machine quotidienne Says:

    […] Chris Kaufmann’s interesting take on the power strip involves outlet and switch boxes spaced along a cord. Great step-by-steps on the project site. […]

  6. Chris Says:

    You’re right about the clamps, of course – I picked up the wrong ones at the store and ended up re-doing the entire strip after taking all these pictures. (And it is plugged into a real surge suppressor). Finally, this is *never* moved, so I didn’t mind using romex which shouldn’t ever be moved unless it’s covered (I think).

  7. Nick Says:

    I was looking at building this for my line dancing group, but now that I see the comments, I don’t think I will. It doesn’t seem to make sense to me if it has to be plugged into a real surge suppressor.

    If I used a panduit power box, and the kind of plug that has the reset button/breaker in it, would I have to wire it up any differently?

  8. Ivan Says:

    Nice Job on the power strip build! However, it might be beneficial if you ground the metal boxes. To do so you can simply remove the plastic ring that holds the two attachment screws on the receptacle or you can tie the bare wire into the metal box using a grounding screw.

    Also where did you acquire your supplies? All the supply houses in my area don’t carry Pass & Seymour devices.

  9. seansy59 Says:

    #1- You should have used 14ga or 12ga stranded copper cord. You can pick this up at any hardware store for about $0.50 a foot. Its used for power tools and extension cords. NM-B is not for any use except permenatly installed on walls.

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