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seriously though....your in a 5 bed house over 3 floors.
Max Zs for 32a ring is 1.37. 80% is 1.1
You record 1.20.
What exactly are you going to do about this ???
I’m going to do nothing.....record 1.20 on the EICR,
and carry on.
In a domestic situation I doubt a ring final would ever operate at a constant 32 amps. On an EICR I would judge the circuit on the particular installation, it's use and projected future loading and note accordingly as and where required.

However if a circuit was subjected to a constant load of 32 amps and I measured the R1+R2 and added the Ze and came up with 1.2o ohms then I would be investigating further as the conductors at the higher operating temperature would have a higher resistance therefore the required disconnection time may not be met.
 
I’m seriously confused here......you’d investigate what and whose orders ??
Your in for an EICR, the Cert asks for MAX Zs.
What code are you going to give a 1.20zs on a 32a ring like in my example above ??
Then, how are you going to explain to the person requesting the EICR that further time...possibly hours, is required for investigating.....even though your recorded results satisfy the cert ??
Finally, which regulation are you quoting to the customer....which justifies your advice for further investigation ??
I’m all ears guys.......I’d love the extra work I could self generate by going down this road.....
 
If your measured zs is too high for the adjusted site temperature at 80% of the max value stated in bs7671 then it stands to reason that at the cables maximum operating temperature at 70 degrees, the resistance will be higher than the required values given to operate the OCPD.
 
noones answering my questions.......how you gonna convince the customer, that although your results meet the certs requirements......you still need further investigation.
And which code and which reg are you gonna quote ??
This is the minimum info that would be required in order to carryout further investigation.
 
Is there an RCD or RCBO fitted to the circuit? Or are we talking old 3036 dinosaur wiring etc. I've been to plenty of new installs where the Zs is oitsido of Zs parameters but protected mechanically. Not much we can do here. Down to poor design really.
 
I check the results as i write them down following testing and the clever bods who set up the NICEIC online portal check them again as you enter them, its rare for a circuit in the domestic arena to be outside of the scope of the online software to check. Think I have only had one circuit that the NICEIC online system couldn't work out the Max Zs for. It saves arguments or debate come assessment time too,
I recall for a while the NICEIC had slightly different values to BYB/BBB and the adjusted values were different again, typical NICEIC making there own version up.

I used the same Certsure software; thought it gave the 100% figure when inputting ocpd type & rated current?
 
its not that I entirely dismiss the 80% thing or don’t see the vague point.....it’s more that I can’t see how I explain to a customer that although my tests say it’s ok and it’s below the value stated in the regs, I’m going to code it and recommend potentially costly further investigation......which I’d struggle to justify with a clear reg.
 
Ironically if the circuit has a 30mA rcd in circuit, then technically you have your fault protection right there.
Poor to design this way on a TN earthing arrangement but on an older install you may have no choice but to record the max zs as say 1667 ohms on the certificate
 
An. Interesting debate so far ....

How about the certificate having tick boxes for 100% and 80%

tin hat on ....

Would never happen....because the iet decide on these things and don’t see it as something they need to introduce to the form.
The NICEIC love to make their own stuff up, to somehow seem regulatory.

If this issue was in any way important....it would have been changed to a mandatory requirement.
 
Essex.....really??? It would need looking at ??
And where does it say that, what code would you use and who is going to pay for your non-regulated investigation ???

Edited to add, I know exactly where the 80% comes from.
I think you are misreading what @essex is quoting.
 
seriously though....your in a 5 bed house over 3 floors.
Max Zs for 32a ring is 1.37. 80% is 1.1
You record 1.20.
What exactly are you going to do about this ???
I’m going to do nothing.....record 1.20 on the EICR,
and carry on.

That would then mean you are doing an EICR incorrectly.

It is debatable if it is a C2 or a FI but it is an ‘unsatisfactory’ all the same.
 
I’m seriously confused here......you’d investigate what and whose orders ??
Your in for an EICR, the Cert asks for MAX Zs.
What code are you going to give a 1.20zs on a 32a ring like in my example above ??
Then, how are you going to explain to the person requesting the EICR that further time...possibly hours, is required for investigating.....even though your recorded results satisfy the cert ??
Finally, which regulation are you quoting to the customer....which justifies your advice for further investigation ??
I’m all ears guys.......I’d love the extra work I could self generate by going down this road.....

I would not investigate anything without the permission of the person responsible for paying. What I would do is one of two things:

1. Mark it on the EICR as ‘FI’ and then submit the report if I felt loose connections could be the cause.

2. Mark it as a C2 as the OCPD would not operate in time which is a direct non-conformance to BS7671. I have not got the book in front of me. Maybe someone se can help.

We do not carry out periodic insepctions to ‘satisfy the cert’. We carry out periodic inspections to issue a report based on BS7671.

I would just use BS7671 to justify any issues I found.
 
noones answering my questions.......how you gonna convince the customer, that although your results meet the certs requirements......you still need further investigation.
And which code and which reg are you gonna quote ??
This is the minimum info that would be required in order to carryout further investigation.

I do not need to convince anyone. My qualifications and 20 years experience should speak for themselves. Couple that with a quote from BS7671 and then it is up to the customer to decide what they want to do.
 
Is there an RCD or RCBO fitted to the circuit? Or are we talking old 3036 dinosaur wiring etc. I've been to plenty of new installs where the Zs is oitsido of Zs parameters but protected mechanically. Not much we can do here. Down to poor design really.

In this instance I woukd record the max Zs permitted as 1667 if the RCD is 30mA.
 
its not that I entirely dismiss the 80% thing or don’t see the vague point.....it’s more that I can’t see how I explain to a customer that although my tests say it’s ok and it’s below the value stated in the regs, I’m going to code it and recommend potentially costly further investigation......which I’d struggle to justify with a clear reg.

You need to get past thinking your test results say it is ok. They are not.
 

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