What on earth ????!!!

[Stanster]

Hi, just to make clear I am not a proffesional but have a problem (or rather a conundrum) that makes no sense at all and wanted to ask your opinion or advice...

(The below was investigated by a proffesional electrician)

A outdoor pond pump is tripping the board when switched on (only after a few seconds) on the outdoor socket. However when connecting the pump via an extension to a different socket (on the same circuit) it works just fine.
The outdoor socket is proven to be fine. Measuirng the pump it proves faulty , but when connected to the extension lead and then measured, there is no fault??!!!.

Now, if there was a short circuit then I can only imagine that it would still trip... So how is it possible that when measuring the pump through it's lead directly it is faulty but when plugged into the extension it is fine....

The electrician advised that he has never seen something like it and can only suggest to have the pump looked at ... anybody has any suggestions?

Many thanks ,

Stan

 

[WarrenG]

When you say you 'measure the pump on its own and it proves faulty' what fault do you have?

 

[Stanster]

Hi - the elctrician said that he tought that there was some sort of short circuit - he used the multimeter , put it on 200 and the outcome was 0.1 (or something similar) doing the same test but then connected to the extension it reads 200. (He must have been measuing ressistance)

Please forgive me for being a little vague , however I am not an electrician but have enough knowledge to understand that what is happening here is rather weird and is defying "the laws of physic"....

 

[WarrenG]

You may find that there is a fault in the cable coming from the pump, you said that its a plugtop on the end so I am asumming that this is flexible cable from the pump and being repositioned to be plugged into the extension lead?

The movement of the cable could be making or breaking a short contact?

 

[Stanster]

Hi,

Thanks for the reply , however movement can be ruled out as both with and without extension the cable has a lot of movement... I am however going to replace the cable to rule out any problems. It still doesnt explain why it trips directly from the pump and not when using the extension cable....

 

[Sparkydan]

Is the Outdoor socket RCD protected? Could be moisture in the outside socket.

I wouldnt have thought anybody could test the pump, i would have tested the circuit and then if it was ok have suggested a new pump.

 

[dom85]

The outdoor socket will have a more sensitive RCD then the consumer unit. Thats if the consumer unit has an RCD.

 

[beaver74]

if th house is installed to the 16th you may find that the pump has an live/earth neatral/earth fault and the second socket you pluged into is not rcd protected as was allowed for socket for in door use and the outside socket will be rcd protected and see a small fault

 

[mrloy99]

Hi,

Thanks for the reply , however movement can be ruled out as both with and without extension the cable has a lot of movement... I am however going to replace the cable to rule out any problems. It still doesnt explain why it trips directly from the pump and not when using the extension cable....

your extension lead might be 2 core only and not have an earth(or could be broken at plug/socket or even inside flex)Can you plug it in via your extension lead to the same outdoor socket successfully? You could have a fault from neutral to earth which wouldn't trip an mcb but would trip an rcd which should detect this fault. It is sometimes very difficult to simply replace the flex on your pump as if it is submersable these are normally factiry sealed and very difficult to make watertight after breaking the seal