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Tt testing


danny7299

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hey up all

I have seen this somewhere , but don't know where...

on the test cerificates, on a TT system , where it says max ZS .. do you put 1667ohm ?

thanks

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yes

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hey up all

I have seen this somewhere , but don't know where...

on the test cerificates, on a TT system , where it says max ZS .. do you put 1667ohm ?

thanks

yes

phtt!!!:_|:(

He's a lazy barsteward that Andyc is :o:|

But he knows that some other poor sod will come and do the rest of the typing hes to lazy to add!!!!

The rest of his sentence should of read..

"Yes" if its a 30ma RCD!, but 500ohm if a 100ma RCD.

and to clarify

loads of TT installations installed PRE 17 edition would have a split load configuration with...

100ma RCD main switch, and 30ma RCD protecting only selected circuits!

So all of the 30ma RCD protected circuits would have 1667ohm max Zs

and the circuits only protected by the 100ma RCD would have a max Zs of 500ohms.

e.g.

consider illustration Figure 3.2 on page 24 of on site guide.

So if you were doing a PIR on old 16th edition TT

or 17th edition TT with some circuits in earthed metal conduit.. etc..

the blanket 1667ohm figure would be incorrect.

And anyway Danny-boy

we all know that you knew the answer to this question was on

Table 41.5, page 50 of BRB, (part of Reg 411.5.3)

and it all revolves around the 50v 'touch voltage

as per bullet point (ii) where it states:- Ra x In equal to/less than 50v

e.g.

30ma RCD: 50v/30ma = 1667ohm

100ma RCD: 50v/100ma = 500ohm.

I just think that both of you Danny & AndyC are a couple of Very Very naughty boys!!!!X(

Not doing your homework proper!!!!]:)

I shall have words with Admin & get you both put on washing up duties for the rest of the week!!!!;\X(

:^OROTFWLROTFWLROTFWLROTFWL

Blushing:x

:coat

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i knew it would be in the book somewhere... but it was late and was easier just to ask the question!!!

i hate washing up!!! Andy C can wash and i will Dry

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i knew it would be in the book somewhere... but it was late and was easier just to ask the question!!!

i hate washing up!!! Andy C can wash and i will Dry

ill wash up. with C4.

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