I’ve bought this timer: http://www.pdlglobal.com/data/product_documents/784_installation_guide_document.pdf

The wiring diagram is in that PDF.

I need help understanding how to wire this up. I’m replacing an existing switch, so there are two phase wires (red), two neutral wires (black) and two ground wires (green/yellow) in the wall. I know which phase wire is live.

I tried wiring it up with the live going to 2, phase output going to 1 and each neutral going to 3 and 4 but that caused the fuse to trip which means it was a short circuit.

I then tested with a non-mains power circuit and found 3 and 4 are the “switch” so I connected the live to 3 and the other phase to 4 and that’s working as a switch but the timer isn’t counting (the neutrals are looped with a cable joiner but not connected to the timer). I now realise this is happening because the timer needs a neutral to complete its own circuit to run the counter.

Advice on this would be really appreciated!

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Attach a red pigtail to terminals 2 and 3.

Splice source red, pigtail 2, and pigtail 3.

Land load red on terminal 4.

Attach a black pigtail to terminal 1.

Splice source black, load black, and pigtail 1.


Note that with this electrical system the hot is red and the neutral is black, not the US color code system.

If you wire this otherwise you can have all kinds of unintended results. If you connect the switch in series with the load in series with the timer, with the timer initially in the "on" interval, it could run until the timer advances to the off position, then both the switch and the timer will turn off. One way to get this odd result would be to wire constant hot / live to 3, NO (4) to load neutral, load hot to terminal 1, and terminal 2 to neutral.

Other hilarity could ensue if you connect the source hot / constant hot to the NO (4) or NC (5).

Since switching neutrals is generally avoided, the neutral should be connected to terminal 2 and no other terminal on the timer switch.

My thoughts would be to very carefully examine the terminal markings and make sure I have identified them correctly, then test the device thoroughly. Also, double check that you have correctly identified the source hot and load hot.

The next test, which the OP has conducted, is to see if the timer runs with source hot to 2 and source neutral to 1. I'd do this again, after double checking the terminal IDs and the source hot.

Next I'd bench test the switch. The instructions don't spell this out explicitly but this is what I'd expect to see assuming it's a typical timer.

With the switch totally disconnected on the workbench, hand turn the timer into the "on" interval you should see

  • Continuity - high resistance between 1 & 2
  • Continuity - zero resistance between 3 & 4
  • No continuity between any other contacts

then hand turn it into the "off" interval and you should see almost the same thing...

  • Continuity - high resistance between 1 & 2
  • Continuity - zero resistance between 3 & 5
  • No continuity between any other contacts

If it passes those tests, and it doesn't operate properly,

  • Thanks bats however have a look at my last comment to Harper. Everything is working apart from the timer keeping track of the time when the timer is off (when the timer pins are in). The timer will happily keep track of the timer when the switch is on (so the lights are on) but not when it’s off. Any ideas? – James Stewart Aug 20 '18 at 9:53
  • I'll update the answer to flesh it out a bit... – batsplatsterson Aug 20 '18 at 10:11
  • 1
    Thanks again bats. I decided to test with a jug cord and the timer worked with just a phase and neutral. Then the lightbulb went off (excuse the pun) - I had the hot phase and load phase mixed up on the wall. Took the timer back to the wall, wired it up with the correct hot phase and bam, problem solved. Feel pretty stupid haha. – James Stewart Aug 21 '18 at 10:18
  • @JamesStewart glad to hear it, that's the main thing! – batsplatsterson Aug 21 '18 at 10:34

Just follow the instructions

As per the wiring diagram in the instructions:

  • The always-hot goes to a cable joiner, then is pigtailed from there to terminals 2 and 3

  • The neutral has a pigtail running from the cable joiner to terminal 1

  • And the switched-hot goes to terminal 4

  • Thanks mate! I’ve wied it up and it seems to be good. I didn’t connect anything to 5, is that right? Not too sure what you mean by Internet jumper. – James Stewart Aug 18 '18 at 20:17
  • Actually, something odd. As you’ll see in the PDF, it’s a rotary timer, so you push the pins out to say when you want it on and the rest are off. When I turn the rotary to set the time, of the pins are off then I can’t hear the rotary turning. However if I turn the rotary to set the time to a position where the pins are on then I can hear it ticking away. Is this because of 5? – James Stewart Aug 18 '18 at 20:28
  • @JamesStewart That may be the case, I'm not familiar enough with that model of timer to judge -- try hooking terminal 5 up to the always-hot as well and seeing what happens. Also, we thank people over here by upvoting and/or accepting their answers :) – ThreePhaseEel Aug 18 '18 at 20:47
  • I’ve played around with it and still can’t quite get it right. Forgetting about the model of timer, the timer itself needs a constant circuit to keep track of the time and then when the timer kicks it, it also needs to start supplying power to the lights it controls. I’ve tried a bunch of combinations but I cannot get the timer itself to keep track of the time while the lights it’s controlling are either on or off. I know I’m close but something in the wiring isn’t quite right – James Stewart Aug 18 '18 at 22:11
  • 1
    I don't believe 3 and 5 should be connected. 3-5 are a SPDT switch, with 3 being common and 5 being NC. – Harper Aug 19 '18 at 6:01

The drawing isn't very well organized.

In your setup, one twin-and-earth cable (red-black) comes from the power supply: it is always-hot and neutral. The other cable (red-black) goes onward to the light and is switched-hot and neutral. Black is neutral in your country.

On the switch, #1 and #2 power the switch itself, and need always-hot and neutral. Or the switch won't work. "Pigtail" black wire on #1, and two red pigtails on #2 and #3.

  • Neutral wires -- join them. Those are the black from both cables and the black pigtail from #1.
  • Always-hot wires - let's power up the switch only. Connect always-hot (red) from the supply cable, and the pigtail from #2. Do not connect the pigtail from #3.

At this point turn the breaker back on. The switch should power-up and do whatever that switch does - though it won't actually switch any lamps. Turn the breaker off again.

  • Always-hot - now we connect pigtail from #3, so #2, #3 and the supply red wire are all joined.

Breaker on again and see if anything goes boom. The switch should do its switchy thing and nothing should go boom. Breaker off again.

  • Switched-hot - finally let's connect the switched-hot (onward to the light cable, red) to the #4 terminal.

Power up, test and you should be done. If it goes boom at this point, most likely the problem is in the load.

Or possibly something is shorting against an earthing wire or metal box when you're shoving it into the box.

  • Hey Harper. Thank you for such a detailed explanation. I tried wiring it up as you said with only the hot wire and neutral (both with and without 3) but the timer will not run. By run I mean tick away counting time. It’s onlt when 4 is wired in with the switched hot wire and the timer pins are on (or the switch is on manual) will the timer actually tick. It’s like the timer itself doesn’t have a circuit and needs the lights it’s controlling to complete it’s own circuit?? – James Stewart Aug 19 '18 at 8:12

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