Low Zs at socket, Any ideas??

[TheCodboy]

Hi all, while testing Zs on a ring final circuit i found one socket to have a particularly low Zs. All others were reading between 0.25- 0.30 but this one was reading 0.08-0.09. Its got a brand new Crabtree double socket installed. A full RFC test has been carried out, and this is the only socket with a reading this low. Obviously i know its better than high, but was just wondering if anyone could shed some light.
Its a TNS system, Ze 0.26

 

[davesparks]

Hi - can't have Zs lower than Ze, so likely a measurement error and I'd just redo it .

Why can’t ypu have a Zs lower than Ze?

 

[davesparks]

Could be the mft, needs a proper tester.

What do you mean? Are you saying that an MFT is not a proper tester?

 

[davesparks]

Was this test carried out with a low current/anti trip test by any chance?

 

[Adam W]

ze

Eh?

 

[TheCodboy]

Was this test carried out with a low current/anti trip test by any chance?

No trip setting

 

[TheCodboy]

Eh?

Fat finger syndrome

 

[Wilko]

Why can’t ypu have a Zs lower than Ze?

Yes, thanks for that
Unfortunately my response was not written in detail but post 26 might help with my thinking at the time.

 

[Adam W]

Fat finger syndrome

Ah.

 

[westward10]

What do you mean? Are you saying that an MFT is not a proper tester?

I was being derisive that these mfts seem to need a bit of pampering for them to function.

 

[davesparks]

I was being derisive that these mfts seem to need a bit of pampering for them to function.

I only have personal experience of 5 MFTs, only one of them had any issue which was a fluke with a dodgy 4mm banana socket. Apart from that they’ve not had any need for pampering

 

[DPG]

I only have personal experience of 5 MFTs, only one of them had any issue which was a fluke with a dodgy 4mm banana socket. Apart from that they’ve not had any need for pampering

1 out of 5 is a very poor failure rate - 20% !!