Dryer on spur trips RCD

[DaveHaw]

On moving to a new(old) house, I added a short (2M) spur to the ring main in order to put my dryer in the cellar. New cable, new socket, wired directly into the ring main MCB of my split CU (Memera 200AD). The dryer display powers up but trips the RCD when a drying cycle is started. I ran an extension lead from a socket on the ring main down to the dryer and it works fine. At this point I'm suspecting the wiring or socket for the spur so check it again but it seems fine (but then it should be, it's all new, and only 2M long with a total of 6 connections to make). I tried a fan heater on the spur and it works fine. I moved the spur to a different ring main but the problem still remains as before.

What's your thoughts guys?

Dave.

 

[Chri5]

Without being there and testing IR and continuity it's difficult to say.

If you are 100% certain the termination is correct then it might be a cable fault, could it have a clip that's punctured it.

One other thing, the neutral at the CU from the spur- is is terminated on the right neutral bar (thinking split rcd board, 2 or 3 neutral bars).

The neutral for say circuits on rcd A must be on the rcd A bar.

 

[DaveHaw]

Thanks Chris,
Yes the neutral is on the correct bar.
I'll replace the cable and try again.

Cheers.

 

[STI]

Going to the ridiculous but just about possible, the new spur isnt by the outlet vent of the dryer is it and therefore when its on the dry cycle it gets damp and trips. Or does it trip as soon as the cycle attempts to start.

 

[DaveHaw]

No, it trips just as its about to start, and its a condensing dryer so there's no vent. I just replaced the cable and theres no change.
I have seen a similar post about a condenser dryer with a short in the heater, but then if that was the case here, why does mine work off an extension lead?? I'll check it out anyway...

 

[DaveHaw]

Ok, I checked the heater and it had water in it, probably from the move. I dryed it out with a hot air gun and now it works.
Which only leaves the question... Why did it work off the extension without tripping???

 

[ban-all-sheds]

1) Check the extension lead - maybe the earth isn't connected/continuous.

2) Maybe the extra resistance of the extension lead was enough to keep the leakage current below the tripping point of the RCD? Shame you've dried it out - it would have been interesting to plug the extension lead into the cellar spur socket....

 

[DaveHaw]

Spot on. Just checked the plug on the extension lead.... Earth had fallen out, L and N had never been tightened!! I'll think twice before borrowing electrical equipment from a neighbour in future!! Glad I took the precaution of not touching the thing when it was on the extension! I'll re-wire the plug before I return it.

Thanks all.

Dave (still breathing!)

 

[ban-all-sheds]

If I were you I'd return it as is and tell him about the fault.

If you fiddle with it you become liable for it.