RCD tripping

[mikeey84]

Hi All, i turned my electric heated towel rail on for the first time in a while yesterday, and it tripped the RCD.

The towel rail is powered by a switched FCU spur taken from the cooker supply cable. (junction box and swithc outside bathroom).

After i flick the switch, it takes approx 30secs for the RCD to trip. The fact that it doesnt happen straight away leads me to believe that its the heating element at fault, rather than the wiring.

To confirm this, my plan is thus; wire the towel rail up with a plug, and plug it into an RCD protected socket. If it trips, then bingo, its the element, if it doesnt, get the BiL round to have a look (he installed it).

Does this sound like a reasonable plan?

 

[ricicle]

It's the towel rail if that's the only thing tripping the RCD.

 

[mikeey84]

It's the towel rail if that's the only thing tripping the RCD.

Hi, sorry my rambling post wasnt very clear, I know it is the towel rail, my question is, is it the element, or something else...

 

[ricicle]

More than likely the element (very slim chance the connections have moisture in them if it is not a sealed unit)

 

[JohnW2]

Hi, sorry my rambling post wasnt very clear, I know it is the towel rail, my question is, is it the element, or something else...

As ricicle said, it's very probably the element, but I don't think that your proposed experiment would help you very much, if at all. Any fault within the towel rail (even wet connections) would result in an RCD trip if you plugged it into a socket - so that wouldn't prove for sure that the element was at fault. In fact, about the only (very unlikely) fault you would identify by that experiment would we wetness affecting just the load side of the fcu.

KKind Regards, John

 

[mikeey84]

Thank you both for your replys.

The purpose of my test was to confirm that it is in fact the towel rail, and not a an issue in the 2 junctions that are downstream of it.

The FCU/towel rail junction is not in the bathroom, so mositure ingress is unlikely.

I think a (returnable) purchase of a new element will be best, that way if it proves to be another fault I am not out of pocket.

Thanks again

Mikeey84

 

[JohnW2]

The purpose of my test was to confirm that it is in fact the towel rail, and not a an issue in the 2 junctions that are downstream of it.

I'm not sure that I understand that. If the towel rail is not resulting in RCD trripping when it is switched off (at the FCU), then it's all-but-certain that the fault is within the towel rail. The only other conceivable possibility (extremely unlikely) is that there is a problem on the load side of the FCU (i.e. disconnected when FCU was switched off). A fault anywhere else on the circuit would result in the RCD tripping even if the towel rail was switched off.

Kind Regards, John

 

[mikeey84]

The purpose of my test was to confirm that it is in fact the towel rail, and not a an issue in the 2 junctions that are downstream of it.

I'm not sure that I understand that. If the towel rail is not resulting in RCD trripping when it is switched off (at the FCU), then it's all-but-certain that the fault is within the towel rail. The only other conceivable possibility (extremely unlikely) is that there is a problem on the load side of the FCU (i.e. disconnected when FCU was switched off). A fault anywhere else on the circuit would result in the RCD tripping even if the towel rail was switched off.

Kind Regards, John

And that is exactly why I come on this forum to ask questions. Good point, well made, and thank you very much

The reason you dont understand it, is because what i suspected was wrong doesnt make sense....

 

[JohnW2]

And that is exactly why I come on this forum to ask questions. Good point, well made, and thank you very much The reason you dont understand it, is because what i suspected was wrong doesnt make sense....

You're welcome!

Kind Regards, John