Overload protection

Roger Hayter · 2019-04-11T09:17:03+00:00

I am confused about this. I have a 2kW heater wired in to a timer. I want to add a frost protection thermostat, which will (obviously) have to get its live supply before the (fused, isolateble) timer. The chosen 1.5mm cable for the thermostat only adds about 300mOhms so is ok for fault protection. But, looking at overload current, does it have to be rated for the full MCB current of 16A, or only for the heater current of about 6A?

Apr 11, 2019 Last reply: 7 years ago 22 Replies

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tabbypurr 7 years ago

after you. Dennis, join the dunce filter.

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dennis 7 years ago

Something like

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With a wifi stat.

Or wire one of these into the spur.

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Roger Hayter 7 years ago

For interest, if anyone else is facing the same problem, the idea of modifying the timer unit to extract an always-on, isolated live does not work, because they have put the timer relay in the supply side *before* the isolating switch. I can see why the timer circuitry needs to be supplied from the supply side, but the relay contacts could perfectly well have been put after the switch.

I will bow to convention (and the regs) and fit an additional FSU.

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