Tripping Rcd

[Sidewinder]

Soul man,

I would have left the cct on the RCD after the changes tbh.

What was the appliance leakage current btw?

 

[soulman]

I dont have a leakage clamp meter, i did IR test the oven and it was clear. I wasn't attempting to mask the problem by putting it over onto the non rcd side, i have been advised to do this, as it was a fixed load and i was surface mounting it. I couldn't see the problem. If it was when the oven was being switched on or in use then maybe something was wrong. But i actually do believe it was what steps said in an earlier post. I would like to know why when the circuit tests out fine you would of kept it on the rcd side.

Cheers

 

[ProDave]

I dont have a leakage clamp meter, i did IR test the oven and it was clear. I wasn't attempting to mask the problem by putting it over onto the non rcd side, i have been advised to do this, as it was a fixed load and i was surface mounting it. I couldn't see the problem.

There's a rule in scientific experimenting. Only change ONE thing at a time.you changed the isolator switch for a completely different one. BUT you never tried it to see if that simple change fixed the fault or not.

Now you will never know (and more importantly we will never know)

By moving it to the Non RCD side, that in itself prevents it tripping an RCD, so you might as well have done just that without changing the isolator switch.

 

[soulman]

Dave as this was in commercial premises, i didn't have that luxury of trying different things, as they have had another spark in already who failed to cure the problem. He changed the 45amp switch left the oven cable just hanging out of the pattress charged them £70 and when they telephoned him, he told them just to live with it. I will however get back to the forum on whether it was the switch as i have to install a couple of sockets for them so i will stick it back over onto the rcd side and see what happens.

Cheers

The 45amp cooker switch was unsuitable that's why i used a 63a rotary isolator and nylon gland.

 

[steptoe]

why not put it on an RCB O,?

that way its still got 30mA protection but no nuisiance tripping for other appliances if it does trip out again.

EDIT, why does RCB O bring up a weird link message?

this rcd & mcb combined' class='bbc ipSeoAcronym'>RCBO

 

[soulman]

Steps, zs was within limits so why is rcd protection necessary.

cheers

 

[Manator]

rcd & mcb combined' class='bbc ipSeoAcronym'>RCBO

 

[Manator]

Your right Steps I will get Admins to have a look and investigate

 

[steptoe]

Steps, zs was within limits so why is rcd protection necessary.

cheers

Im not saying it is necessary,

does the manufacturer ask for 30mA protection? a lot do.

just curious as to why rather than solve the problem you simply chose to mask it.

 

[soulman]

So steps what would you suggest if you dont mind me asking which is why i posted in the first place.

Cheers

 

[steptoe]

find out if the oven has a leakage to earth under normal running would be my first test.

 

[soulman]

Cheers steps i will borrow a clampmeter and measure the leakage when i'm there next.

 

[steptoe]

needs to be a low current one soulman,

a normal clampmeter wont read low enough, remember, we may be looking for mA here more likely than not,

most clampmeters wont read below 1/2 amp, :|

 

[soulman]

Hi just to update, moved this circuit back over onto the rcd side to check new rotary isolator this still tripped the rcd when opening the switch. i checked leakage current when the oven was in operation, the leakage clamp meter i was using showed there was definately some leakage, unfortunately the clamp meter wasn't very good and showing 300ma leakage which would definately trip the rcd when running. I am still extremely confused as to why this trips the rcd only when turning off at the isolator and not when running normally or turning on.

Cheers

P.s i will be treating myself to a decent earth leakage clampmeter in the next few days.

 

[Sidewinder]

Contact Megger Mark one of our forum sponsors then soulman, he'll sort you out a cracking deal, I'm sure!

 

[Manator]

Did you try using a time delay RCD? Better than no protection it currently has!

The cause of the earth leakage should always be investigated firstly, the oven is obviously at fault the leakage could be due to the bad design in installation.

Insulation is never definitive and leakage is always assumed, I install medical equipment that requires almost perfect installation procedures, touch voltages and leakage are a vital part of correct installation. Some equipment I install requires RCD protection as low as 5mA, would be pointless putting that on a time delay.