Reverse Polarity (after power stops)

[pebe]

It depends on your timer. If it uses a relay to drive the load, then no problem. You will need a diode only if there is a warning about using it with an inductive load.

But if you want to be sure, connect a 1N4001 across the coil. Connect the diode with its cathode to positive side of the relay output.

DPCO is Double Pole Change Over
DPDT is .DP....Double Throw
DP2W is DP....Two Way

They are all the same.

Best regards to a Yankish and his dad from a 'sassenach' in Scotland