The clocks on Intermatic timer run on-time for years
If this a new timer >> then buy another one, and swap out the insides without changing the box, and return the bad one.
Voltage variation will not affect clock speed. The only electrical thing that affects speed would be the cycles. Your household has 60 cycles. The clock motor is 60 cycles.
When you connected wires, the wires fit under a metal clamp and the screw pushes the metal clamp down against the wire > only copper wire should be under that clamp > if some insulation is also under the clamp, then the contact might not be 100% all the time, which would stop the clock. Check that all your wire are down tight.
If wires stop in a junction box before arriving from breaker box, there might be a loose connection in that box. Trace back your line, especially if this is a pool control with a junction box.
A shorting breaker can stop voltage from time to time, making it appear as if the clock is slow. If one leg of the 240V stops, the circuit stops. You can check breaker for loose screws. Does breaker feel warm? Is there a crackling sound when you jiggle breaker. You can put your timer 240 lines on similar sized 240 breaker and see if clock runs slow ... that would indicate whether the problem is clock or breaker.If timer is old
, the plastic clock gears can get worn. The metal timer gears rust or clogged with dirt. Snap out the insides and inspect for rust and dirt. Use a little WD-40. Turn off power since WD is extremely flammable.
Snap the manual override back and forth. Does it snap crisp? Or is it sluggish? The clock motor turns the dial until the tripper encounters a metal lever. The Clock keeps pushing the tripper until the tripper clicks the metal lever >>> which happens to be the same lever the manual override is connected to.
So if the manual override is very hard to push ... ... a sluggish manual override might slow the clock. You might put some grease on the lever where the trippers touch.Finally, the clock motor can go bad
$16, Grainger sells 240V T100 series clock motorhttp://www.grainger.com/Grainger/wwg/search.shtml?searchQuery=Wh40&op=search&Ntt=Wh40&N=0&sst=subset