Zs fault

[lady electric]

Another question i remember from my exam - and i did answer it but want to check if i got it right!! what to do in the case of a Zs fault -

 

[mogga]

Zs "fault"? as in high Zs reading?

 

[lady electric]

I cant remember whether it was high reading, all i remember was fault, what are the steps to do in the case of a Zs fault?

 

[Octopus]

????????????????????????????

 

[mayfair]

Sorry ..................Totally Confused

 

[kamkam]

call a plumber?

 

[lady electric]

thanks guys!!

 

[telectrix]

really need to see the Q. high readings can have several causes. a Zs fault seems to suggest that a reading can't be obtained.

 

[lady electric]

unfortunately i cant remember it word for word but it was definately along the lines of.... you find a fault during a Zs test what would you do .....and my brain went blank!!!

 

[Des 56]

The wording of the question needs to be checked Lady of Ogwr

Your second post seems more to the point
It may be that you have measured a high reading and are being asked what to do to find that high reading/ problem/fault

See if you can get hold of the question and post it word for word,then these good folk will do what they can to go through it with you

 

[Guest 004]

if you have a Zs fault, the circuit needs to be first isolated, then locked, as under fault conditions the circuit will not trip in the time required by BS7671.

You would need to check the circuitry for loose connections first, if none could be found, then the circuit would then require an improvement by means of a lower rated or type MCB, 20 down to 10, or C down to B etc, if this still cannot be obtained. It would need to be rewired.

 

[johnboy6083]

an RCd can also be used, but in my opinion, i would rather cure the problem than the symptoms, so would rewire if possible.

i would see which of the conductors is giving the high reading. if it is the CPC, then you can use paralell paths to reduce this via trunking, tray ect. its not good practice, but is an option.

 

[malcolmsanford]

You also have the use of RCD .....................and if you really wished supplementary bonding, but don't think many would go down that road

 

[i=p/u]

rcd would cover it for me , if no mess allowed, nice new floors and ceilings

 

[Guest 004]

rcd would cover it for me , if no mess allowed, nice new floors and ceilings

you guys seem to be forgetting that this is AN exam question!

oh did I pass, yes, did I get distinctions, yes...............

 

[i=p/u]

its what they teach you these days and reason i said that is because we were talking about the exact subject on monday. not always an option for new circuit or breaker device to be reduced, thats all folks!!!!!!!!!!!!!!!

 

[geoffa]

had a similar problem to be solved in the 2391 practical.
Zs value was too high for ADS.
Assuming the system is TN-C-S
Number of solutions:
Check R1 +R2 equals what you would expect using the resistances/m as shown in OSG page 166. Could indicate poor connections
Check the MCB type as it could be a C type where it may be possible to have a B type depending on what the load type is. B types have a higher max Zs value compared to C's
Could reduce the length of the circuit
Could use cables for the circuit having a larger csa

 

[lady electric]

Thank you all for your input - appreciated

 

[telectrix]

and if all else fails there is always the fast track course 7 weeks learning how to lie through your teeth, become a .......... politician, lawyer, estate agent, salesman, banker, care home manager, any manager, sure there's more.......

 

[i=p/u]

7 weeks is a long in a classroom, il stick to 1 day per week