new running machine trips RCD

[toastydave]

Hi guys,

My sister has bought this new reebok running machine and its unusable in her house!

when ever the motor starts it trips the RCD in the consumer unit (a eaton MEM 2000 with a 100A 30mA RCD) and the whole house goes dead.

so she called the store where she bought it and they came out and changed the motor, this failed, so they sent a totally new one to replace the once she bought. this also trips out the RCD.

The only solution the shop can now offer her is a refund, but my thinking is whatever she buys next will do the same as the problem seams to be in the house.

I had a look in side the machine and it has a DC motor to drive the running belt round. From the motor comes three wires, Live, negative and earth to the chassis, if you disconnect the earth from the motor, but leave the earth's connected for the frame and control unit to earth, apart from the added danger potential every thing runs fine. Of course I can not and did not leave it like that...

your ideas please, the rcd looks to be of a quick acting type, perhaps one with more delay?

Thanks

Dave

 

[Steve]

The problem is not the house. Unfortunately some appliances are simply unsuitable for use on such sensitive RCD devices. The only solution i can think of is investing an a split load consumer unit, and run the running machine from the non-RCD side, though it may still need to be on a 100mA RCD if you have a TT earth.

 

[toastydave]

Thanks Crafty!

not the best news, but I did need the truth!

Thanks

Dave

 

[Maxxy]

I got a running machine from argos, works fine. Rcd in the garage and in the house.

 

[davy_owen_88]

Try running it with as many watery appliances unplugged as possible (kettle, immersion heaters, washing machines etc.)

It could be that you have a high level of normal background earth leakage, and the new running machine is just pushing it over the RCD's threshold.

I'm assuming by your comment about the whole house going out when the RCD trips that you are on a TT supply? I would advise you to get a sparky out to fit a 100mA S-type RCD as the incomer and use that to feed the lights and certain fixed equipment and then protect the sockets with the 30mA RCD. This should reduce the levels of leakage and should solve the problem.

 

[Jaymack]

Try running it with as many watery appliances unplugged as possible (kettle, immersion heaters, washing machines etc.)

Agreed and have a test carried on the RCD, if inconclusive.

I would advise you to get a sparky out to fit a 100mA S-type RCD as the incomer and use that to feed the lights and certain fixed equipment and then protect the sockets with the 30mA RCD.

Agreed. The 100mA RCD is fitted for overall fire protection to property etc: and doesn't give personnel protection; hence the 30mA unit for sockets - most important where a portable running machine is concerned.

 

[toastydave]

Hi all, thanks for all your help!

I really appreciate it!

I'm not sure what type of earth the house is bonded to, I guess it would be a TT type, as its far out in the country and I carn't see them running an earth all the way back to the generator. Is there a easy way to tell, for interests sake?

I gave a bid of a red herring a bit back It would seem, its only the Sockets on the RCD (a 100A 30mA trip)

Thanks again for all your help!

 

[davy_owen_88]

A TT supply will have the main earth cable running to an earth rod driven into the ground somewhere. All other earthing types have the earth cable running to the cut-out or attached to the incoming cable sheath.

 

[Podooser]

, its only the Sockets on the RCD (a 100A 30mA trip)

Surely it cannot be TT if this is correct.

 

[tim west]

Although it depends on the quality of the machine and how it operates, maybe there is a variable speed control (as opposed to the cheapy switched step controls) that could be wound all the way down before switching on the machine and then slowly raise the speed rather than whacking it up to running speed too fast. like a dc faceplate starter(showing my age here) care used to be of essence when operating these devices in order to limit inrush or starting current, it's probably the imbalance of the heavy inductive load that's tripping the RCD, maybe the wife is a bit impatient to start her exercise regime?

 

[toastydave]

Hi all, Thanks so It looks like it must be a TN earth system...


Hi Tim,

I think It is an inductive thing because yes it does have a fancy Variable speed control, if the speed is very very low <1Kph it does not trip the sockets any faster and pop.

Thing is, is there any way so fix it?

well there must be a way, but like everyone I want it for cheap!

Thanks