I am replacing an Intermatic mechanical T104 single circuit timer with a new Intermatic P1353ME unit that can control 3 individual equipment items in addition to the timer clock.

Each of the three circuits can control either 120v or 240v equipment items independent of the timer power source. Can this timer be used with existing 240V, 20 amp, 2 wire plus ground power feed from the panel?

I plan to use this 20 amp circuit to power three equipment items at 240v. Total load is below the 80% load for the 20 amp circuit.

With an existing 2 wire dedicated 240v circuit, what leg is considered "Line" and what leg is considered "Load"?


2 Answers 2


This timer can be hooked up to your 220V, 20 AMP, 2 wire plus ground circuit from the panel. Since you don't have a neutral you won't be able to ever run any 120V equipment unless you change your wiring. This timer have the ability to switch both hots on a single 220V load but not on three separate equipment items. You'll only be able to switch one hot on each piece of equipment. The other hot will always be connected to a load wire.

With your 220V circuit, the two hot legs from the panel will be your line 1 and line 2. Your wires from your three pieces of equipment will be your load 1 and load 2 for each piece.

  • I had planned to use all 240v equipment, so 120v is not an issue. So, it's OK to leave one wire hot. Thank you. May 19, 2020 at 18:27

I have used that model of timer, I believe you only break 1 leg of the 240v line so if you use L1 to the timer then on the output feed that to the L1 lead (or load) L2 is always connected to the load.

  • Ed, so it's OK that one leg is always connected and hot. Thank you. May 19, 2020 at 18:25
  • Yes that is a common way to control 240v devices you just need to remember that because there is still 120v to ground on the devices (I have been bit a few times over the years when I did not throw a breaker). Make sure to turn off if changing the voltage for the timer, I think it was lug 1&2 you pul L1 & L2 on then jumper one of them to lug 3, 5 & 7 switch on 240v and it will be powered up then 4,6,8 are outputs 1,2,3 and the always hot to the device is the one you did not jumper to the line lugs.
    – Ed Beal
    May 19, 2020 at 18:38
  • I thought I would mention I started out using these timers but changed to sto1 from Intermatic very similar programming but the sto1 cost 35$ if I need more than a 20 amp load I drive a magnetic contactor. The sto1 runs off a battery (cr2) so the voltage doesn’t matter , I have lighting circuits on these handy little timers all over the plant 120-277v using the astrometric function saves additional $ as the lights are cycled with dusk and dawn events. The battery’s last about 2 years so when the first one fails I change them all out. Our power co gave us additional rebates for doing this.
    – Ed Beal
    May 19, 2020 at 18:56

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.