[The Carpet Cleaning Pro]

I have a prochem steampro and when switching on the pump it blows house fuse. I have wired direct to cable, bypassing machine and pump works fine. The pump wires go to a small box to pink and yellow wires that go to switch on machine. What is the small black box and could this be the problem?

[john martin]

when u wire the pump direct are u connecting an earth to it ?  its possible the motor is developing a fault and tripping the rcd ,thats the first thing i would do , connect the earth to it .    Im not sure from you your description if the little black box is a relay or some sort of inline noise supression ,  if itys a relay ... that could develop a fault , u might be able to google some numbers on it an order a replacment .  Also check for the obvious , loose or touching wires , the switch it self ...and dampness .

[The Carpet Cleaning Pro]

The pump is earthed. I have checked all wires and can not find anything. The red and black wires from the pump connect to a Small box like thing that appears to be gel like but is not soft. More like a resin I suppose. This is where connection to the switch takes place.

[The Carpet Cleaning Pro]

The little black box has now been replaced. It contains diodes turning direct current to actual current.  Or could be the other way round. The fault is still there. The pump is earthed and wires all seem to be ok. The switch has been checked and is ok. The problem is when on machine the pump trips electric. When not on machine and wired directly by cable it works fine. Any ideas?

[Mike Gwilliam]

When the pump is on the machine and disconnected from the mains, check that there is no continuity between live-neutral and earth while the switch is on and off positions.  Is the machine clean from carbon dust from the motors?

[Scott Blaney]

I had a similar issue and ended up replacing the big multi block connector where all the wires run to.

I re terminated all the cables so they were fresh connections before re fitting. 

Think its been a mixture of corrosion and old age with the bare ends of the wires.

[Mark porteous]

Replace the wiring from pump to rocker.