Testing Off Peak Supply?

[claret73]

Was on a job over the weekend fitting a new board & an extra board for their Off peak storage heaters. As the Off Peak doesn't come into play until Midnight, how do you live test the installation?
Trainee question lads...
Cheers

 

[NoSparks]

I disconnet the Off Peak and cross couple with the main supply just for the functional testing. You can't do a true Ze a the board but it should be the same as the main supply Ze. Ze at source is of course common.