testing novice

[Dalf]

Hi guys just after some help. I have not done alot of testing so I apologise if this is a stupid question.

Ring main. Getting end to ends all ok. Breaker stays on but as soon as my tester is plugged in to get zs or an appliance is plugged in it trips the rcd. Also when tester is plugged in it says connect error.

What is usually the most common fault for this?

Thanks

 

[somersetsparks]

eh? you'll have to elaborate more but so far it sounds bloody dangerous!

 

[chrish_1977]

What tester are you using, some robins, you have to bypass the rcd to get a zs, what other tests have you done, what about ir? Is it any appliance or one thing in particular, lots of variables to answer first I'm afraid

 

[somersetsparks]

EDIT - I think I read the OP wrong ;-)

 

[Dalf]

Done ir all ok. It's as soon as it has load on circuit it trips rcd.

 

[chrish_1977]

Has to be a fault with something, what's the full story, diyer?

 

[Dalf]

No. I have not barely done any testing as I work for a big company who have just testers.but had to go to a job which is ending an the lad who wired it is on holiday, it was supposably tested but they plugged in fridge. Trips rcd straight away. So tried something different an exact same thing

 

[Dalf]

Tester was using 17 series megger.

 

[somersetsparks]

Sounds like a dodgy RCD, use your testers ramp setting to see what threshold it trips at.

 

[Octopus]

Hum... could be many things. Could you post a picture of the CU without the cover?

 

[jaydee81]

are there any other circuits on the same rcd and do they work ok did you check polarity could be neutral earth reverse in socket

 

[Thomas123]

I'd do a ramp test, but it's sounds like a neutral fault, if it only trips when there is load, test ir on all the circuits on that rcd.

 

[Dalf]

Sorry guys its actually on its own rcbo

 

[Harryb]

Check neutral tails from the RCD's to the individual bars are in the right bars and not crossed, that's caused me a headache before

 

[chrish_1977]

Sounds like you might have the wrong neutral/line in the rcbo, double check that first

 

[Octopus]

Own RCBO, get those sockets off the wall and see what happens.

 

[Dalf]

All sockets where checked and they looked fine but then ran out of time so back in tues for further investigation. Did try another rcbo an still the same.

 

[Ronyg]

Definitely a polarity issue somewhere!

 

[Marvo]

If you tried another RCBO and the circuit passed an IR test then my money is on a neutral fault, crossed, borrowed or otherwise incorrectly wired.

 

[tony mc]

I would dead test the cct and test every point with the figure of 8 method (again) IMO something has been connected up incorrectly. I don't use a 1700 series Megger but surely the tester is pointing to a connection issue and plugging something in the RCD is seeing the fault!