How do you test r1+r2? Any tips on doing it faster

[Heisenberg]

Piece of cable with 2 crocodile clips.one on the earth bar,one on the bus bar .switch on the mcb that is being tested. you get your reading and check your labelling at the same time

Next circuit,off with one mcb,on with the next and not a screwdriver in sight

How did you get the front off of the CU then :tongue3:

 

[Des 56]

don't like that. any resistance within the MCB will give false readings. i take the L out of the MCB and clip from the cable end to the E bar.

A very quick and simple action tel is to take a reading through the mcbs
It would indicate any high resistance mcb, this resistance is also part of the earth loop which is a bonus

Unless circumstances don't permit,taking out conductors from the mcb (which can create a problem where none existed previously, if the tester fails to remake the connection correctly)is a waste of time and needless disturbance where none may be needed

 

[Des 56]

How did you get the front off of the CU then :tongue3:

I hold my hands up to that one

 

[martinh287]

I was always taught not to disconnect stuff if it was not needed for the reason above when it came to testing. I would always test through a mcb for high resistivity though to ensure a good connection

 

[odawire]

my new megger tester has an r1+r2 Zs test mode, it saves the Ze reading and just subtracts it from the Zs, what do you guys think of that as I always thought of that as a cheats way of testing, but its certainly quicker

 

[DNS1]

Personally I take the line and earth out and clip them together with a Wago...

 

[Geoffsd]

my new megger tester has an r1+r2 Zs test mode, it saves the Ze reading and just subtracts it from the Zs, what do you guys think of that as I always thought of that as a cheats way of testing, but its certainly quicker

Why would you want it when measuring Zs?

Presumably you already have the R1+R2 value and have already added Ze .

 

[odawire]

Well what that setting suggests to me is that you can obtain the r1+r2 value by doing a Zs test, which is easier and quicker, but it seems like a cheat

 

[DNS1]

Well what that setting suggests to me is that you can obtain the r1+r2 value by doing a Zs test, which is easier and quicker, but it seems like a cheat

It's really not cheating!

 

[Octopus]

Personally I take the line and earth out and clip them together with a Wago...

And when you've done the R1 + R2 you can then do the IR!

 

[Geoffsd]

Well what that setting suggests to me is that you can obtain the r1+r2 value by doing a Zs test, which is easier and quicker, but it seems like a cheat

But you must have already done the Ze.

I take it it can't work out what is R1+R2 and what is Ze from a single measurement.

Plus - it does not detect parallel paths so R1+R2 will be lower than the actual value
(unless you enter Zdb to be deducted).

Just being picky as Flukes have always given you R2 when measuring Zs but this obviously includes the distributors earth.

 

[Bengston]

croc clip method (short out the MET with the bus bar) and test at the furthest point.

 

[odawire]

Yes but I need to do the ze anyway, parallel paths are the only problem with that I suppose, but do you think that's an acceptable way to obtain r1 +r2? because its so much quicker

 

[telectrix]

getting the value of R1+R2 from Zs is OK (IM0) on a EICR where the circuit is energised already, but on initial verification, you must measure resistances before energising.

 

[odawire]

oh yea, im sure no one would ever dream of energising before measuring resistances :angel_smile: