MK 63amp RCD that fails Ix5 test everything else tests fine on the board

[stuarth]

I have a brand new MK 63amp RCD that fails Ix5 test everything else tests fine on the board, I tested with all circuits off everything unplugged so swapped it for another thinking must have a faulty one but the same result, it will trip at 50ms and ramp tested at 33ma, ze=0.18 what could be happening? any advice on what could be wrong would be greatly appreciated.

 

[The Ghost]

smart meters tripping nearby rcd

That is interesting. Wonder if they use any xformer in them to power the ethernet they have? Is this domestic or commercial @stuarth.

 

[stuarth]

domestic, unable to get in today but should on monday

 

[Deleted member 26818]

There’s no requirement in the 18th edition for RCDs to trip in any particular time.

As for this testing with all loads disconnected, what’s that all about?
Yes Mrs Miggins, your RCD works fine, as long as you don’t switch anything on.

 

[Andy78]

There’s no requirement in the 18th edition for RCDs to trip in any particular time.

As for this testing with all loads disconnected, what’s that all about?
Yes Mrs Miggins, your RCD works fine, as long as you don’t switch anything on.

The note in 643.8 makes reference to compliance being achieved in terms of additional protection when the 40ms at 5x rating is met.
I just see that this information has migrated from section 415 and found a new home.

 

[Deleted member 26818]

The note in 643.8 makes reference to compliance being achieved in terms of additional protection when the 40ms at 5x rating is met.
I just see that this information has migrated from section 415 and found a new home.

Yes, but it’s a note not a requirement.
The requirement now, is just to have 30mA RCD protection

 

[Andy78]

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.

 

[stuarth]

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.

 

[The Ghost]

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.

 

[stuarth]

16mm main earth, TNCS 10mm bonding to gas & water

 

[The Ghost]

25mm²? For TN-C-S I don't often find a reading that high usually around the 0.1 ohm. Anyway just a thought.

 

[Wilko]

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.

 

[Deleted member 26818]

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.

 

[Deleted member 26818]

So the RCD should trip within 40ms when tested at 5x or more.
Not sure if my tester will use a higher current, or how to set it so it will.

 

[Midwest]

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?

 

[stuarth]

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?