Calculated Zs on an EICR

[TJC1]

Got asked to carry out and EICR on a doctors surgery (NHS)

On the previous inspection done 5 years ago, they stated under limitations.. The Zs reading of each circuit has been calculated.

In theory if you have a Ze + R1 + R2 then yes you would get the result, but isn't it still good practice to do your Zs test?

 

[buzzlightyear]

testing is now in order to see if it compliances, with the value of the mcb .

 

[Sintra]

Personally speaking I always prefer to measure Zs as this is the only test that confirms the complete circuit including protective devices. There’s always a possibility that you can have a high resistance accross a device that would result in a high impedance at the end of the circuit. This will never be found by calculation.

 

[TJC1]

testing is now in order to see if it compiles .

??

 

[buzzlightyear]

??

read GN note 3

 

[TJC1]

Most circuits that are not protected by an RCD are buried in the wall less than 50mm. Would you make a note of this C3 for every circuit?

 

[buzzlightyear]

Most circuits that are not protected by an RCD are buried in the wall less than 50mm. Would you make a note of this C3 for every circuit

yes .

 

[Risteard]

Most circuits that are not protected by an RCD are buried in the wall less than 50mm. Would you make a note of this C3 for every circuit?

Why not make a general observation rather than repeating it for each circuit?

 

[Ian1981]

Why not make a general observation rather than repeating it for each circuit?

Very true, otherwise you could have numerous codes related to the same thing

 

[cliffed]

Got asked to carry out and EICR on a doctors surgery (NHS)

On the previous inspection done 5 years ago, they stated under limitations.. The Zs reading of each circuit has been calculated.

In theory if you have a Ze + R1 + R2 then yes you would get the result, but isn't it still good practice to do your Zs test?

Why wouldn’t you do a zs test.

 

[Blissof89]

GN3 states that calculating you Zs is perfectly acceptable. Almost seems to advise it over live testing.

 

[telectrix]

GN3 states that calculating you Zs is perfectly acceptable. Almost seems to advise it over live testing.

written by suits at a desk, instead of us poor sods in the real world.

 

[Ian1981]

The regulations also state that zs can be obtained by other methods than direct measurement so technically it’s not against regulations if you don’t do a direct measurement.
As it’s an EICR I do direct measurement and don’t bother with the R1+R2 method
I use a wander lead connected to the MET and connect to exposed conductive parts(lights and the like) to verify they are connected to earth

 

[Blaspark]

Most circuits that are not protected by an RCD are buried in the wall less than 50mm. Would you make a note of this C3 for every circuit?

C2 according to napit codebreakers book. Their opinion not mine.

 

[Blaspark]

written by suits at a desk, instead of us poor sods in the real world.

Is it not actually better for various reasons. You can't do a live test for zs without bonding connected which will give you a lower value. However building works may permanently remove that parallel path.
If you use ze + r1 + r2 you get the highest possible value which will be more resilient.
No?

 

[westward10]

C2 according to napit codebreakers book. Their opinion not mine.

You not got a recycling bin for waste paper.

 

[telectrix]

it's a C3 all day long. only way you could justify a C2 is potential danger from a numpty nailing or screwing the cable.if it's within prescribed zones, then numpty deserves whatever he gets.

 

[Blaspark]

You not got a recycling bin for waste paper.

Why so harsh on the book. It's very difficult to decide what to put on the eicr personally I like to avoid that bs and defer to an "authoritive source"

 

[westward10]

It isn't an authoritative source though Code designation should be judged from knowledge, experience and any factors which are present on the day. You should not need a guide to steer you through an EICR and if you do maybe you need to question your competence for the task you are undertaking.

 

[Ian1981]

The code breaker book advises a C2 code for tails that are not the minimum required 25mm.
I mean where in bs7671 states that tails must be 25mm?
What if you have 16mm tails? Why is that a C2 if they are acceptable for the load they are connected to and satisfy the requirements for fault protection?