R2 option over R1+R2

[44ALLAN]

??Because you can touch the outside metal casing to items if they are fixed and for whatever reason can't be accessed, moved or just generally to expensive to get involved with. Common sense no??

Yup you have it in one..............best explanation ever well done mate you have it sussed

 

[Regs]

Now......this should be burnt into your mind,

Zs = Ze + (R1 + R2)

Ah come on your not being fair here, that is burn trust me but:-
You said you would have to know your Zs, when infact you would have to know your Ze also
And even if you knew these you would have to rearrange this formula to something like
Zs-Ze-R2=R1
Cheers 4 help anyhow.

 

[Regs]

Yup you have it in one..............best explanation ever well done mate you have it sussed

Pff and i didnt even get a thank or like
lol, ive learn something then.

 

[Regs]

But you shouldn't subtract Ze from Zs to get (R1 + R2).

Why not? apparently calculated R1+R2 is perfectly acceptable, defo sure i read that in regs if some 1 could help clarify that, cheers.

 

[44ALLAN]

Pff and i didnt even get a thank or like
lol, ive learn something then.

I'll give you a thank 'and' a like if in your next post you tell me the difference between Zs and Ze...............can't be fairer than that mate.
you have 5 minutes to look it up

 

[Sintra]

Why not? apparently calculated R1+R2 is perfectly acceptable, defo sure i read that in regs if some 1 could help clarify that, cheers.

Absolutly not. Love to know where it says that.

 

[Pondy]

Do I get a prize for knowing the answer

 

[44ALLAN]

Do I get a prize for knowing the answer

Soggy conductive mars bar from last night ok?

 

[Regs]

I'll give you a thank 'and' a like if in your next post you tell me the difference between Zs and Ze...............can't be fairer than that mate.
you have 5 minutes to look it up

only just read- Ze is external
Zs is whole shabang anything a bit harder?

 

[Richard Burns]

If you measure R2 this is your confirmation that your cpc is safely connected from the MET to the accessory.
Once you know this and that your IR tests are OK, then you are safe to start live testing.
You would then use Zs to confirm polarity and that your circuit would meet the required disconnection times.

 

[Tuttle]

Why not? apparently calculated R1+R2 is perfectly acceptable, defo sure i read that in regs if some 1 could help clarify that, cheers.

Rearranging Zs = Ze + (R1 + R2) to (R1 + R2) = Zs - Ze looks good on paper, and is mathematically correct, but in practice you can measure R1+R2 a lot more accurately than Zs or Ze.

Also, Ze is measured with bonding and parallel paths disconnected whereas Zs is measured with parallel paths in place, so subtracting Ze from a measured Zs doesn't necessarily give R1+R2.

 

[ChrisElectrical88]

Zs - Ze to gain R1+R2 is not acceptable at all.

Ze + R1+R2 to gain Zs is acceptable if I am correct.

On initial verification I will always do all tests and on EICRs I tend to do R2 and Zs of each circuit.

 

[Regs]

If you measure R2 this is your confirmation that your cpc is safely connected from the MET to the accessory.
Once you know this and that your IR tests are OK, then you are safe to start live testing.
You would then use Zs to confirm polarity and that your circuit would meet the required disconnection times.

Thank you very much Mr Burns, perfect answer of what i was looking for. I couldn't get my head around the fact that an R2 test alone was sufficient. This only confirms continuity as you have kindly pointed out.

It is very confusing as on the test sheets it does say R1+R2 OR R2, implying just an R2 would be acceptable. I was scratching my head thinking how is that going to comply with the required times.

Well i'm glad some 1 understands me at last.

 

[Octopus]

R2 is best used when doing EICR's to light fittings.

For new installation work the R1+R2 is best, then you can confirm polarity at the same time.

 

[Regs]

Absolutly not. Love to know where it says that.

Well you guys obviously know a lot more than i do, so o.k but isn't there not some exceptions?