Discuss Very high Zs reading in the Electrical Forum area at ElectriciansForums.net

M

mspms

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Good evening all. I wonder if anyone could give me a steer as to why I am getting very high Zs readings. I have been testin a circuit that has a R1+R2 of 0.23 ohms but I seem to be getting Zs reading on L-E of + 40ohms. L-N is coming in at 0.2ohms. The incoming fuse is a 63amp BS1361 an RCD main switch protecting all circuits. All other tests are fine. I am wondering whether it could be my meter not reading correctly on the Zs test. Any ideas?

Thanks all.
 
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What's your Ze mate? When was your meter last calibrated? It could be a few things what earthing system is it?
 

telectrix

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try taking as reading on the L busbar. if that is high, then it's due to internal resistance of RCD and/or MCB. flick them on and off a couple of times. if that reading is OK, try at the terminals of the socket, not the front. try flicking the socket switch/es on/off.
 
R

Rauer

  • Thread Starter Thread Starter
  • #5
try taking as reading on the L busbar. if that is high, then it's due to internal resistance of RCD and/or MCB. flick them on and off a couple of times. if that reading is OK, try at the terminals of the socket, not the front. try flicking the socket switch/es on/off.
Never considered that but will remember it for future reference!!
 
M

mspms

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  • #6
TN-C-S. Ze seems very good at 0.09ohms
 

telectrix

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what was the pefc at socket?
 
M

mspms

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  • #8
Thanks for your suggestion I will give it a go. Just to add more pain, I thought I would try a reading from a socket in my own home and again I'm getting +40ohms. Just coincedence?
 

telectrix

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mft leads. ????
 

Strima

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What are you using to test the socket? Have you tried testing at the terminals on the back?
 
M

mspms

  • Thread Starter Thread Starter
  • #11
Sorry teletrix. It was a long day. I gave up and came home. The house is empty at the moment so no chance of any mishaps!
 
M

mspms

  • Thread Starter Thread Starter
  • #12
My Ze was really low at 0.09ohms. My meter has just been calibrated and it is a TN-C-S.

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I'm using my 3pin plug and leads.
 
R

Rauer

  • Thread Starter Thread Starter
  • #15
Have you zero'd your leads on eloop?
 

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