Discuss MK 63amp RCD that fails Ix5 test everything else tests fine on the board in the Electrical Forum area at ElectriciansForums.net

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Yes, but it’s a note not a requirement.
The requirement now, is just to have 30mA RCD protection
The reg I quoted requires RCDs for additional protection to be tested to verify effectiveness.
The note defines the time that should be met to verify effectiveness.

If the time cannot be met then it could not be deemed effective and therefore not compliant ?

Just how I read it.
 
I have read this as well and I agree with @Andy78 the question is what can I do to improve the disconnection times I need a solution for the customer.
 
what size is the main earth and is the connection Ok? Is it TNS or what? I was just thinking to increase the main earth size or improve the earthing arrangement.
 
Last edited by a moderator:
16mm main earth, TNCS 10mm bonding to gas & water
 
Hi - perhaps confirm your tester is set to AC (I think these MK RCDs will be AC type, rather than A). If still no good, perhaps try a higher test current and see what happens. The reg now allows for more than 150mA to be applied to achieve less than 40ms. I don’t like it, but that’s what I understand.
 
The reg I quoted requires RCDs for additional protection to be tested to verify effectiveness.
The note defines the time that should be met to verify effectiveness.

If the time cannot be met then it could not be deemed effective and therefore not compliant ?

Just how I read it.
Yes, it does say that.
 
Someone posted on here about Hager Type A’s and ramping up the test current, using a Megger 1740 series, I think.

Was it a vid by Sparky Ninja?
 
Someone posted on here about Hager Type A’s and ramping up the test current, using a Megger 1740 series, I think.

Was it a vid by Sparky Ninja?
 
I'm sure I'm missing something here and will be promptly corrected, but.... the RCD doesn't trip within required times so change it for a new one that does.
 
I'm sure I'm missing something here and will be promptly corrected, but.... the RCD doesn't trip within required times so change it for a new one that does.

You are correct as far as I know, the tripping time is set by the manufacturer and a property of the individual unit.
 
Has all the other initial testing been ok?
Yes all tested good, nothing to suggest there would be any issue had high resistance on the cps on both ring circuits but after investigation a couple of sockets had there sleeving clamped in and a couple were lose but retested good.
 
That's not right, if it trips at 33mA then its faulty, it should trip between 15 and 30
Its the second RCD they can not be both faulty surely?
 
We had about 8 MK 6a RCBOs recently with a similar fault. Tripped fine at 1x, at 5x or more they would not trip at all. Tried 3 different test meters.
 

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