Changing a DPST to SPST Timer

[Pointyhead]

My Timex timer broke recently (plastic shaft inside snapped) and no longer will spin. I bought an Intermatic T101M as a replacement. Beside the fact that mechI got a super deal on it on eBay, but didn't realize that it was a SPST as opposed to the DPST that the Timex is. Which means that the terminal strip is different. On the DPST, there are 4 terminals, 1-4, with a black and white set coming from the breaker box and a black and white set going to the pool pump. The new timer only has 3 terminals, the A post and 1 and 2. How exactly should this be wired? Anybody else have this problem?

 

[JasonLion]

You need to get a different timer if you need a DPST switch. The T101 only switches a single line. You need a T104 if you want to switch two lines.

 

[danpik]

Is your pump a 240 volt or 120 volt unit? I am inclined to think 240.

 

[Pointyhead]

The pump is 110. I just changed it out this spring. It's a Hayward 1.5 super pump. In fact, I don't have any 220 lines in my breaker box.

 

[JasonLion]

When using 115 volts, there is almost never a reason to use a DPST switch. Do you know what was being switched on each pole of the old switch?

 

[Pointyhead]

When using 115 volts, there is almost never a reason to use a DPST switch. Do you know what was being switched on each pole of the old switch?

No, there's just the 4 insulated wires coming in to the timer box, 2 white and 2 black (plus 2 grounds). The only thing on the circuit is the pool pump.

 

[tim5055]

No, there's just the 4 insulated wires coming in to the timer box, 2 white and 2 black (plus 2 grounds). The only thing on the circuit is the pool pump.

Sounds to me that they were switching the neutral for some reason?? Without being there with a meter it's hard to tell.

 

[danpik]

Looks like the Neutrals connect to the A terminal, line to terminal 1 and load to terminal 2

 

[Pointyhead]

Looks like the Neutrals connect to the A terminal, line to terminal 1 and load to terminal 2

That's what I'm thinking. The clock motor is pre-wired to A (neutral) and hot to Terminal 1.