Need confirmation on Zs results.

[stevethesparks]

There is only one RCD on the current board

 

[telectrix]

if you test the RCD again , you'll probably get lower readings. if it's not tripped for a while it could have got a bit sticky.

 

[Octopus]

There is only one RCD on the current board

In which case its not a hi integrity as I think of hi integrity as 2 x RCD's + a few MCB/RCBO ways!

 

[stevethesparks]

I am contemplating putting in a Hi Integrity one in place of the current one. I did actually mention that in my fist sentence. I was doing some checks before hand as he has just moved in.

 

[Guitarist]

Depending on the RCD type, you have upto 300ms at 1x to play with, so while higher than we usually find, it's not outside acceptable tolerance.

 

[ARK]

the earth loop can be massive with an rcd in line, well over a 1000 ohms and still comply

 

[Guitarist]

the earth loop can be massive with an rcd in line, well over a 1000 ohms and still comply

One would never accept a high earth loop reading on a TN system though, simply because it has an RCD in-line. If it's high, then there is either a fault, or the system wasn't designed very well.

 

[Jay Sparks]

the earth loop can be massive with an rcd in line, well over a 1000 ohms and still comply

Put your tin hat on and get ready.........

 

[pencilpusher]

the earth loop can be massive with an rcd in line, well over a 1000 ohms and still comply

Not for me I'm afraid. I always design to meet the MCB disconnection times on TN systems. I certainly don't put all my faith in the RCD to be happy with resistances that high.

E54 will have something to say about that too, I'm sure!

 

[Engineer54]

In which case its not a hi integrity as I think of hi integrity as 2 x RCD's + a few MCB/RCBO ways!

I don't, a high integrity CU is an all RCBO board! lol!!

 

[Engineer54]

Not for me I'm afraid. I always design to meet the MCB disconnection times on TN systems. I certainly don't put all my faith in the RCD to be happy with resistances that high.

E54 will have something to say about that too, I'm sure!

What can you say to statements like that?? He's just another brainwashed fella that considers RCDs as the electricians cure all for badly designed and/or installed electrical work that don't/can't meet primary Zs values!!

 

[Silly Sausage]

the earth loop can be massive with an rcd in line, well over a 1000 ohms and still comply

That is my nomination for 'Post of the Month' :smilielol5:

What are the odds that someone would pass a circuit with a 4 digit reading?!?!

 

[Deleted member 9648]

the earth loop can be massive with an rcd in line, well over a 1000 ohms and still comply with meeting required disconnection times

If you'd included the bit in red you'd be correct in theory.....in practice though an earth loop that high (and the reasons for it being that high) is not going to comply with anything else.