Oil filled electric radiator heater tripping RCD

[Koray]

Hi all,

An oil filled electric radiator in my office trips the RCD as soon as I plug it in. I checked the resistance between Live, Neutral, and Earth on the plug. Between L and N depending on heat setting, my meter measures 50-100 Ohms. When I measure between L and E, or N and E, I receive about 25-30 Ohms reading. I opened the front panel and checked cables and circuitry: everything looks OK. When I disconnected the heating element from the rest of circuitry, I get readings as shown in the image below, where one coil seems to be shorting the earth (casing). This looks like a lost case, right?   ---->



Thanks!

Koray

[ebastler]

Yes, that would be my interpretation -- the upper coil has a short to ground, about midway. And yes, I don't think it can be repaired in a safe way. Depending on the brand and age of the heater, you may be able to purchase a new heating element, or may be better off replacing the whole unit.

[SeanB]

Those elements are easy to replace, place heater so element is on top, and unscrew it, and replace with a new one, not forgetting to replace the o ring seal at the base of the threads. You might lose a drop or two of the oil fill, but nothing to worry about.  The elements tend to have a very generic size and thread, despite the brand of the unit, as most are made to the same pattern, with only the brand applied being different, along with a slightly different style of side plastic case.

[TheMG]

Similar style of heating element to what is found in electric water heaters. The resistive element is inside of a metal tube which is filled with some type of heat resistant insulating material to isolate the resistive element from the metal tube, which is grounded.

What has likely happened is that either by a fault (hot spot) or manufacturing defect, the resistive element has migrated through the insulating material and come into contact with the grounded metal tube.

Such a fault is not repairable as the heating element can not be disassembled. The only solution is to replace the heating element.

[Koray]

Thank you all for your comments and suggestions! I now checked online if there are replacement heating elements: yes, there are plenty of them at very affordable prices (around $10USD in my home country). I will order one. Thanks a lot, again.

K.