RCD tripping

[Monsieur27]

Hello all,

i have an issue with a commercial dishwasher who has been checked by an Engineer with no fault.

RCD trips as soon i switch the wall socket,however i've unplugged every plug i have and surprise it does not trip.

now,i've tried to see if have split load,correct me if i'm wrong,i did switch RCD(got just one) off and i ended with , 3 MCBs on the right of the RCD still working(2xlights and one socket),does is mean i have split load?

now,to confuse you more,i've tried to plug the dishwasher into the socket i have mentioned above and no power to the dishwasher even though that the socket works.

dishwasher is 15amp.

can anyone help.

 

[jj4091]

You need to post pics of your consumer unit & demonstrate what trips & what does not.It does not sound like you have a split load consumer unit. I presume you are using a commercial d/w in a domestic setting.

 

[Monsieur27]

Thank you for reply.
not in domestic setting but in coffee shop.
i forgot to add we never used it before and it's a second hand
the dishwasher is phase 1,not used before.

Untitled

• Monsieur27
• 19 Mar 2015
• 1

the cover has been removed to give more details.

the 3 MCBs on the right of the RCD still works when the dishwasher trips the RCD.
i take it the 3 MCBs are not protected by RCD .
many thanks

 

[jj4091]

OK yes you do have an old type split load board, not the latest dual RCD type. Yes that is correct, only the main switch isolates those 3.
To start with could it be something as simple as the 13A fuse in the plug has blown, if it is drawing 15A as you say you may need to connect it to the supply by a different method( e.g. double pole isolator) & have it on an independent supply. Did the engineer not mention this to you? And how could he test it properly if he could not connect it to a supply?

 

[Monsieur27]

the fuse has been tested and when we unplug all the plugs in the shop the D/W does not trip and we get power to the D/W.

the engineer mentioned you may need to create a new circuit.

he checked the D/W by checking any earth leaking or faulty PCB,he also checked the power block inside the machine...tried different power cable....etc.

do you know why it doesn't trip when all other plugs are unplugged?

will RCBO solve the issue by swapping the MCB to RCBO?

THANKS

Untitled

• Monsieur27
• 19 Mar 2015
• 1

 

[jj4091]

So to summarise, it trips the RCD when when plugged into any socket circuit that is connected to it but works as long as nothing else is plugged in, but does not work on the socket on the non RCD side. I suppose that it could be that earth leakage in various appliances are combining to be enough to trip the RCD (30mA) but that does not explain why it does not work in the non rcd socket. A wild guess would be that the heating element is beginning to fail on the dishwasher but that would have shown up if the engineer used an insulation tester (eg megger) to check it. Can you ask if he did that rather than just a multimeter or portable appliance tester. Another thought is that heating elements can sometimes absorb moisture through standing unused & you say it is second hand so I guess it may have stood for a while. If you can get it to work with other things unplugged you could try running it through a complete cycle which would dry any moisture out of the element when it heated up the water. You could then try it again with everything else plugged in.If you continue to have problems the only other thing I could think of would be to get an electrician to instal or convert one of the other ccts. to an independent supply. It may be simple or may not but only a site visit would ascertain that.