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J

jason_exact

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I have a Megger CM500, just back from calibration so its working! I want to carry out an RCD test on the RCBO on a oven circuit but the tester only has a 2 wire test leads and a moulded plug set of leads for sockets. How do i test the circuit with only 2 wires?

I did phone MEgger and they said you can but i have forgotten what they said to do!

Also how do you carry out a Zs test on the same circuit with only 2 wire set of leads?

This is my first post on here so all help welcome please!
 
S

Spudnik

  • Thread Starter Thread Starter
  • #2
Is there not a 3 wire test lead available to purchase?

Seems odd that it has no trip function with only a 2 wire lead set as i think it uses 25A test current.

Maybe check the Megger website?
 
J

jason_exact

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  • #3
thanks

there might be a 3 lead, but im testing tomorrow morning! just trying my house at the moment!

Ever done any 2 wire RCD or Zs testing?
 
D

DanBrown

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  • #4
Sorry Jason, im not sure i can help on that one.
Are you sure it only does 2 wire tests??
 
S

Spudnik

  • Thread Starter Thread Starter
  • #5
You cant do 2 wire RCD testing as far as i know.

2 wire Zs test is between live & earth only but its test current is around 25 amps and will take out any most MCB's under that.

You really need to try and get the 3 wire set to be able to perform the no trip loop test.
 
J

jason_exact

  • Thread Starter Thread Starter
  • #6
im pretty sure it does 3 wire testing as well but i dont have the leads for it. Also when i spoke to megger they said i only needed 3 wire for phase rotation 3 phase testing. They said you can test the rcd on radial without sockets on with the 2 wire but i cant remember how.

have tried a couple of ways but nothing working.
 
S

Spudnik

  • Thread Starter Thread Starter
  • #7
Do you not have a manual?

They are normally quite detailed

Have a mooch here:

Megger.
 
Last edited by a moderator:
J

jason_exact

  • Thread Starter Thread Starter
  • #8
thanks people, if all else fails look at the manual!

all sorted.

the 2 wire does work for the Zs test black clamp on earth red clamp on live.

the 2 wire rcd test works when you press the type button on the tester to change it to the dc sensitive option.

Hopefully will work tomorrow on the job.

cheers anyway!
 
S

Spudnik

  • Thread Starter Thread Starter
  • #9
Ah yes, the age old advice...

Rtfm!!!
:D
 
S

super spark

  • Thread Starter Thread Starter
  • #10
A Zs test is between the line conductor and the cpc, A rcd test creates an imbalance between either of the live conductors and cpc therefore why do you need or want a three probe test ?????

line - cpc , trust me it will work.
 
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