pond pump trouble

[traineelectrician]

ive been trying to get these pond pumps to work and its not happening for me.. probably a simple answer to it.. the circuit is: An RCD plug with a 3 amp fuse in, 2.5mm artic cable coming from that to the outside through conduit into a junction box. from that there is 3 x 0.75mm.
1 = and independant pump
2 = a second pump
3 = a uv
( the second pump and the uv work together)

so what i did is try each circuit on there own to see which one was tripping them out..

pump one tripped as soon as i turned it on, then tried second pump and uv together they worked, so presumed it was the first one tripping it all out.... 15mins later the second pump tripped out and the filter box was empty??? tried it again tripped out, filled the filter box up with water and it ran til was empty again... so neither of them seem to work. power is obviously getting to it. i thought the rcd plug must be nackered (i havent changed it to check) but why would it work for a bit for one and not at all for the other

its ran perfectly fine for a few years... i have no test equipment btw.

any ideas or answers would be great.

 

[Steve]

When you "disconnect" the pumps individually, what are you ACTUALLY doing? Does the junction box contain switches? If so, these are likely single pole and therefore the neutral will still be connected. This can still trip an RCD.

If you are actually disconnecting them with a screwdriver, this would suggest the problem is the UV filter. Try operating the UV filter on its own (after making sure the tube cant harm anything with heat - they rely on water to cool them, if you can remove the tube and operate it in free air but dont look at it)

Look in the UV filter - are any of the connections wet? If so, how? In particular, check the ends of the bulb. Check the seals at the ends of the tubes / quartz sleeve.

Alteratively, disconnect the UV filter and then try to operate the pumps.

One thing is for sure. If either pump is knackered, you MUST NOT try to repair it. They are sealed for life.

 

[traineelectrician]

thanks for the reply...

in the junction box its just a choc block, supply in one side and the 3 loads to the other, so tried individually that way. the UV is new to me, theres a pipe coming from the pump to the UV then back out the UV into the filter box (tank) and apparently it lights up at night at the ends of the pipes to show that its on.
i will try what you said but the pump cant be pumping it through to the UV for it to filter.. and also the other pump cuts straight out on its own as well when i tried that, surely it cant be coincidental that they bothgone at the same time??

would trying a new supply and RCD plug be an option?

 

[Steve]

its possible that the actual supply cable is damaged - between the plug and the junction box. inspect this. its rare for pond pumps to develop faults because like I said, they are sealed for life and very reliable.

 

[traineelectrician]

ok thanks for the advice steve, i shall try it out.