Cirrus

Wired a kitchen this week and the earthing system is TT with a 30mA RCD up front. Got round to testing and everything was going fine until I tried to test for R1. The reading I got was >2000 so basically showing open circuit. I have continuity and Zs but cannot seem to get my R1 +R2. I had this last week on a TT system and I know it can be calculated but can't work out why the Fluke MFT won't give me a reading when I don't get probs on any other earthing system such as TNCS / TNS. Is it just a fact that this happens with TT systems?

Unregistered

sorry to pick faults but if its showing open circuit on R1 how have you got continiuty?

Grae79

Or Zs?

TonyM58

Cirrus,

ok my head is fried now

R1?

how do you measure R1? or why?

R2 yes, R1+R2 yes, but R1????

like to help fella, but i think you would need to explain this test to me

the type of earthing system will only affect your Ze,Zs, PFC's and possibly your RCD times.

and a 30mA up front? oh dear, may as well throw the regs away

Cirrus

Sorry, was typing this on the way out so think I have screwed up what I was trying to explain. Will have a look at the test sheet and come back to you. As for 30mA up front - it is an existing crabtree starbreaker board. I have just added a new ring and cooker circuit.

TonyM58

when you say 'up front', is the RCd being used as the main isolator in the CU?

be interesting to know about the R1 thingy.......

Cirrus

yes, the rcd is also the main switch. Board is probs about 20 years old but am now confusing myself and think that it is a 100mA rcd

TonyM58

if its the main switch then it should be a 100mA S-Type

ian.settle1

Tony

If it's a ring circuit then he has got to measure r1, r2 & rn for ring continuity.

Maybe he is getting mixed up with upper and lower case letters.

TonyM58

could well be Ian,

of course if its r1 and its open circuit, then this would epxlain why hes still getting Zs (although at an untrue value)

just shows that the three stage ring test works!

regards

Tony