Pump tripping rcd

[240sparks]

Just tested a rain water pump with my portable appliance tester & it tested ok (earthing & insulation resistance). Plug it into the power point & it trips the rcd as the pump starts. The power point is fine have meggered the wiring etc. Any ideas?

 

[Spudnik]

Were you able to perform an earth leakage test on the pump?

 

[Shinner]

The pump might draw a lot of current on initial start up, what type of RCD is it? May require a C or even D

 

[Guest123]

The pump might draw a lot of current on initial start up, what type of RCD is it? May require a C or even D

Hey.

An RCD monitors earth leakage current, not overload. The MCB for that circuit would (or should) operate before the RCD in the event of overloading as it is rated lower i.e 16A MCB possibly, and 63A RCD. The pump circuit for example could possibly carry 63A of overload current before the RCD operated and obviously the cable would not be able to cope with that, and thats not what RCD's are designed for.

RCD's are RCD's you dont get B,C or D type only in MCB's.

The pump may only be faulty once it's submerged in water or once water is being drawn through it? Did you test it dry i.e out of it's resevoir?

Cheers

 

[240sparks]

Thats correct. It is on a 20A circuit. It is the rcd that protects this circuit that trips. Its not a submersible pump. Its an above ground with inlet hose & outlet hose to house. I tested it connected to plumbing. I am assuming that it has earth leakage when it runs (pumping water). I tested pump on a circuit without rcd & it works fine.

 

[WarrenG]

What type of 20A mcb is it? Is the mcb tripping as well?

Sorry just read your bit about testing the pump without the RCD and it works fine.

Try the pump on its own with the RCD - i.e switch off all other circuits protected by the RCD.

You may have a combined leakage across a group of circuits that tops out when you run the pump?

 

[Spudnik]

I tested pump on a circuit without rcd & it works fine.

Which is why you need to try and perform an earth leakage test on the pump as it seems to be leaking more than 30mA which (i assume) is what the RCD is rated at.

Either that or maybe the RCD is overly sensitive.

 

[240sparks]

The rcd is rated at 30mA. What is the best way to test the earth leakage? Is there a tester for this?

 

[Spudnik]

Is there a tester for this?

Yes there is but they are very expensive to buy at the moment.

Hopefully with the 'RCD everything' reg the price may drop as more people purchase them.

In the meantime if its small enough, maybe you could take the pump home and test on a different RCD to eliminate possible RCD fault, or borrow or hire one?

Just an idea.

edit: Not as expensive as i thought actually:

Mastech MS2007B Leakage Clampmeter Details - Test4Less Tester & Tool Distributor

 

[240sparks]

Replaced the rcd with new as thought the old one to be suspect. Definately something with the pump. Will need to try & get an earth leakage meter. Thanks

 

[WarrenG]

Replaced the rcd with new as thought the old one to be suspect. Definately something with the pump. Will need to try & get an earth leakage meter. Thanks

Did you try my suggestion earlier in the thread?

You have stated that you have a Pat Tester, surely you can test the pumps leakage with that if need be?

 

[240sparks]

Yes. I tried the pump on rcd by itself. Still tripped. I thought it would show up on my appliance tester too. Obviously not as good as I thought it was.