R1+R2 Calculations from ZS

[telectrix]

and into the equation comes the internal resistance of MCB and RCD........affecting the value ofZs.

 

[nickblake]

Glad im not with the NIC then , they should get a life , so how do they do a dead Ze test , and its good to be a naughty boy ,lol , gee ill have to wear my wellies to do it then , think they need to get out of there offices and come into the real world

 

[nickblake]

and into the equation comes the internal resistance of MCB and RCD........affecting the value ofZs.

Blimy telex you had your sugar puffs this morning then

 

[keefy]

According to the NICEIC Nick we can't do live Zs testing as it is dangerous and classed as live working ..............your a very very naughty boy.

Yea! Do a dead one instead!!!

 

[malcolmsanford]

Yea! Do a dead one instead!!!

hmmmmmmmmmm Zs = Ze+ (R1 + R2) was always a dead one, well dead by calculation I should add

 

[telectrix]

Blimy telex you had your sugar puffs this morning then

just had me brekky. coffee and a smoke. nailed that earth fault. Ze=0.16 TNC-S, Zs 347. RCD internal resistance 347. sheesh. bloody MEM rubbish.

 

[RogertheBodger]

Well done Tel, one for your memoirs?

 

[Sintra]

just had me brekky. coffee and a smoke. nailed that earth fault. Ze=0.16 TNC-S, Zs 347. RCD internal resistance 347. sheesh. bloody MEM rubbish.

Happy days mate you will know to look out for that again.

This is why a Zs test must be carried out after R1 + R2 as it is the only test that actually goes full circuit. (not aimed at you Tel but for general info)


Sent from my iPhone using Tapatalk.

 

[Guest123]

Has anyone read the article in Marches Proffessional Electrical magazine regarding 'live working' taken from the HSE document.

Seems we can after all...........

 

[malcolmsanford]

Has anyone read the article in Marches Proffessional Electrical magazine regarding 'live working' taken from the HSE document.

Seems we can after all...........

Lenny I can't get that out here, any link perchance mate

 

[Chr!s]

Heres a link to a document malcolm

http://www.hse.gov.uk/pubns/indg354.pdf

 

[malcolmsanford]

Heres a link to a document malcolm

http://www.hse.gov.uk/pubns/indg354.pdf

Many thanks Chr!s ...........scholar and a gentleman

 

[nickblake]

My hair looks very much like lennys profile pic during live testing , spot on sintra just What i think

 

[mickeyspark]

Thanks Guys, apparently we have to have a MWC, thought I was right about R1+R2 calcs, this web site is so good for scratching the head and finding info however trivial it may seem. Its a huge world of Electrical knowledge we have to have in our heads, we can't pretend to have all the answers.

Thanks Mickeysparks

 

[ganz]

If
zs=(r1+r2) + ze

cant you just transpose the formula to read r1+r2 = zs - ze ?

 

[Sintra]

In a word no.

 

[ganz]

how come?

 

[yellowvanman]

Because when you measure Zs, you could have parallel paths (pipework etc.). When you measure R1 + R2 you should be measuring just the cable resistance, ie. conductors not terminated at a busbar.
So generally worst case Zs = Ze +( R1 + R2), and when you measure Zs it will probably be less (due to the parallel paths). Thats the theory anyway!

 

[telectrix]

how come?

because if you are doing things right, you do not energise the circuit until you have proved it with dead testing, i.e. R1+R2 and IR test.

 

[ganz]

i know you are right, but in theory transposing the formula should lead to the same result