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Posted By Topic: Voltage to earth

nofidea
Sep 25 2019 18:30

Hello all, saw a new 1 today so thought would seek opinions.
Was repairing some type of cooking plate, after opening it up I noticed 1 element was connected to 240 volt and no probs, but the 2nd element was fed from a transformer ( 240v - 14VAC) but one of the 14volt output wires is connected to the end of the element but also the earthed frame.
Its only 14 volts, but I have never seen any appliance with it wired to earth as part of the circuit.
Thoughts?
   

Someone
Sep 25 2019 20:52

If this is an isolating transformer, it's fine.

What you have is essentially a PELV or separately derived system.
   

DougP
Sep 25 2019 23:08

Yes PELV.

It's so that if there's a fault in the wiring or the transformer or power supply where the LV ends up getting through to the ELV side, the ELV side being earthed should cause the fault protection to operate.

In the old days before Class III or SELV supplies, the secondary of control transformers and even doorbell transformers were also earthed.