Possible Job For Tomorrow

[Andrewr3]

Reported as occasional trip of an RCD. Leakage current noted 2.5A when cooker switched on (which is on a 30mA RCD). Could be interesting.

 

[Darkwood]

Are you asking for hints/tips or just informing us of your working day ahead?

 

[Pete999]

Whats the photo about Andy?

 

[uksparks]

If the cooker is on and it's leaking >30mA why has it not tripped then?

2,500,000 / 1000 gives milliamps

mA = 2500mA

IR = 230 / 2500

IR = 0.092 Ohms

if I'm correct in my calculation you have a almost a dead short somewhere? Either this is correct or I'm going to look like a right plonker.

working it the other way just to check...

R = IR x 1,000,000

R = 92,000

I = 230 / R

mA Leakage = I x 1000

mA = 2.5A

 

[uksparks]

That's based on 2.5A sorry, not 2.35A

 

[Marvo]

The 'occasional trip' and the 2.5A leakage current don't really go well together. 'Won't reset' would be better.
Measuring the leakage down the CPC or main earth doesn't show you what's being lost down parallel paths so it's not the most accurate way of testing..

 

[uksparks]

The oven must have an element on its way out or something.

 

[uksparks]

The 'occasional trip' and the 2.5A leakage current don't really go well together. 'Won't reset' would be better.
Measuring the leakage down the CPC or main earth doesn't show you what's being lost down parallel paths so it's not the most accurate way of testing..

I can't see how the RCD would hold if it 'is' leaking that much.

 

[uksparks]

If my calculation is incorrect please could someone with a little more understanding correct me.

 

[Octopus]

I can't see how the RCD would hold if it 'is' leaking that much.

Is it a single RCD or dual RCD board?

 

[Marvo]

You can't use the current in mA, you need to use 2.5 Amps instead.

 

[uksparks]

Is it a single RCD or dual RCD board?

It may be accumulated unless everything else is disconnected but still, I would expect to have to use an elastic band or a lock out device to hold the RCD on.

 

[Andrewr3]

Are you asking for hints/tips or just informing us of your working day ahead?

It has got me thinking and cannot work on it further until landlord gives permission. Thought it might give a few of you a puzzle to think about on your sunny Sunday afternoon. I am puzzled as to why the RCD has not tripped because outwardly it looks like a Neutral Earth fault, but I have not checked yet to find out more specifically where the the problem is. The lighting and smokes are not on the RCD. Also as someone, has mentioned here already, the occasional RCD trip could be unrelated to this high residual current. Hopefully I'll get the job and will be able to satisfy my curiosity.

 

[uksparks]

You can't use the current in mA, you need to use 2.5 Amps instead.

can you expand on that please.

 

[Andrewr3]

Oh, and I quickly checked the RCD was working fine on x0.5, x1, and x5 etc.

 

[MDJ]

The Rcd is faulty and there is a dodgy ring on the hob, test the rcd as per usual, at times half, one and five on 0 and 180 degrees, that will sort that bit out, then you can look at whats going on with the oven.

 

[Marvo]

If the cooker is on and it's leaking >30mA why has it not tripped then?

2,500,000 / 1000 gives milliamps Leave I in Amps, not Milliamps

A = 2.50A

IR = 230 / 2.50

IR = 92 Ohms

if I'm correct in my calculation you have a almost a dead short somewhere?

Not a dead short at 92 Ohms

 

[uksparks]

The Rcd is faulty and there is a dodgy ring on the hob, test the rcd as per usual, at times half, one and five on 0 and 180 degrees, that will sort that bit out, then you can look at whats going on with the oven.

It might be a gas hob ;-)

 

[guest119]

Is the leakage coming in or going out?

Boydy

 

[uksparks]

Not a dead short at 92 Ohms

I didn't think it looked quite right, thanks for that!