In article , cj
writes
Hi
Whew whatever happened to manufacturers putting 5A dc 3.5A ac on their
switches.
As for your heater its impedence depends on the manufacturing process some
panel heaters have a punched strip (looks like a row of hairgrips on a
plate) these have a lower impedence compared to the coil wound fan panel
heaters.
In any case i would recommend a 10 or 13A rated stat due to the start surge
of the heater and the back EMF at switch off under load.

As Andy G points out there is no switch on surge and a quick fag packet
calculation suggests the inductance of a 300 turn coiled, air cored
element would be of the order of 500 microhenries so there's not really
enough energy flying about to call up the inductive rating of the stat.

It's nice to derate contacts by quite a bit to extend life but there's
really no need to do overboard. 5A vs the nominal 4.35A is a little less
margin than I'd like but this sounds like a Horstmann/Tower programmable
stat so I wouldn't be expecting 20 years out of it in any case.
--
fred
Plusnet - I hope you like vanilla