RCDs tripping

[wrighty]

hey, i was rung today by my dad to come and look at a glasswasher that is causing the main RCD incomer to trip every time it trys to cycle.
This glasswasher is in a pub, over the last 2 days the landlady said every time she tried to cycle the dishwasher it tripped all her pumps out. The glass washer powers up fine and fills with water everytime it tried to run a cycle tho it tripped the RCD on the fuseboard, its a really old fuse board didnt catch the name but im going bk tomorrow after work to investigate more. my thoughts was could it be the element that is nakard and causing this tripping? if not any ideas?

also the shower in the flat above the pub is causing tripping aswell. The fuseboard in the flat is a dual RCD split board, the shower switch has recently been changed and so has the shower as the last 1 was nakard. now this is the interesting part. when the shower switch is turned on it powers the shower no problem, then when you push the power button on the shower it causes the opposite rcd to trip not the 1 feeding the shower side. Ive not had any experience with split rcd boards being in the commercial side of things. and this 1 is baffling me a touch. now i havnt had the cover of the board off to see whats going on inside ill be doing that tomorrow on my return visit. i just thought id post on here to see if any of you have had similar situations of this. also to maybe save myself some time when going back tomorrow. i dont have full test equipment available either this is a favor for some1 so just trying to help out without it costing them a fortune.

is it a coincidence these are tripping together or could it be something further down the line?

 

[ringer]

It would mean that only the shower would trip, and not half the circuits in the house.

Wouldn't really tho would it, if both rated at30mA it would be pot luck which one went out first

Even if the other side pops and the shower keeps running, then the shower side will exhibit a difference in current between L and N on that side, and should therefore trip as well.

 

[Dan the spark]

Lost me there ringer, still don't get what ur gonna gain from putting it on a rcbo on a split board?

 

[Paul.M]

edit. paul.m is close to you if you get stuck.

"He's off to have a look at it after work" and "its in a pub." Count me in but your driving .

I'll pm you my number if you need a hand.

First place to look at is that new switch, it worked ok before that was changed? Next step the cu, visual first then an IR test as above, if that's not the problem then clamp meter cpc at the cu as it could be accumulated earth leakage.

You say it trips when the shower on/off button is pushed. Let's have a look at the element, probably the same problem as the dishwasher in the pub.