Socket Zs High

[Moses]

"I think you must agree, that if 6A a breaker will trip with a 7A fault current(CPC-L), then it surely will trip with a 8A current short circuit(L-N)."

Will it?????
ever???
in 0.4s ??

Geoff, my friend, Zs is the impedance of the circuit, and not a current.

Lister, my friend, a 6A type B CB will trip in 0.4Sec with a minimum of 30A current. 7A & 8A were given as examples.

There fore 230V/30A = 7.67 Ohms is the theoretical max Zs for a 6A type B CB.

 

[Moses]

Originally Posted by Moses
Thank god we r on the same page

I agree with your comment of a Hi z on the N wire.

But that's another reason why Zs is measured between L-CPC, it ensures the earth fault durations are limited.



high Z...well that`s changed then....a minure ago it was Zs....


Yes but no, but yes but no, but yes but no Glenn

That Hi Z on the N wire is a fault, faulty connection.!!!!!!!!

 

[Moses]

Agreed to a point (Hence "around" 0.35ohms)
I believe the ring in question is fairly small and the figures the op states seem way off by 1 and a bit ohms....seems alot to me, especially as he states these sockets are all on the ring final and not spurs.

Sipmles he has not zeeored

or

he has a low battery

or

He has a faulty meter

 

[Jonny66]

Points to something along those lines agreed....where is the OP????

 

[Moses]

Points to something along those lines agreed....where is the OP????

Well confused by now i bet!!!!!:laugh3::laugh3::laugh3:

 

[GLENNSPARK]

Sipmles he has not zeeored

or

he has a low battery

or

He has a faulty meter

so if he hasn`t `zeeored`...or the batterys are low....hmm, so its a faulty meter then is it Moses?....possibly...but rather than just condemn the meter..would you not check the leads first?....

 

[Guitarist]

I had to send my Megger 1730 back a couple of weeks ago because the EFLI test at a socket (using plug adaptor OR on the terminals) was way higher than I was expecting. As has been said, it can be the internal resistance of the MCB/RCD so that would have to be deducted.
All that said, once I got my new 1730 and did the same tests, they were very close to Ze+(R1+R2), so it was definitely a faulty tester in my case.

Edit... Forgot to add. I have to do a 3-wire no-trip test, as the 2-wire is always at least 0.5 ohms higher!

 

[GLENNSPARK]

but my point was you dont just condemn the meter....its only as good as the test leads you are using....

 

[Guitarist]

but my point was you dont just condemn the meter....its only as good as the test leads you are using....

Totally agree mate.

 

[Geoffsd]

Sorry for delay - something crashed.

Geoff, my friend, Zs is the impedance of the circuit, and not a current.

Yes, I'm sorry. I should have written -

But that's what Zs IS ​- a measured value to determine prospective earth fault cuurrent

The same test between L & N is to determine the prospective short circuit current.

The greater of these two is the prospective fault current.