NICEIC Certification Scheme Consumer Unit Installation Up to Scratch??? NICEIC approved Installer.

[westward10]

Sorry my mistake. The Ze was 0.3. I did a quick pefc I think it was, and it was nice and high. Could've been 1600amp.

It was my house that was 0.19Ze and that's definitely a tns.

You cannot base the earthing system from a Ze

 

[shinypen]

Sorry just meant it is visually unambiguously a tns at my house. And low ze. I'm confusing the issue just ignore that!

 

[telectrix]

Off topic, Tel how are the dogs doing?

she's holding on to them. can't believe it. nesting but not dropping yet.

 

[Pete999]

she's holding on to them. can't believe it. nesting but not dropping yet.

Typical always keep you waiting, sleepless night ahead then?

 

[The Ghost]

With Amd 3 pfc is calculated as 230 x.95 (Cmin) = 218.5/0.3 = .73 Ka (pg. 127 GN3) Not that it makes much difference but it certainly would if you had 0.03 which is becoming more common. I think you need to set your loop test to high output as no trip loop test can be innacurate especially on Ze test.

 

[Octopus]

FWIW there is NO requirement to upgrade the CU tails to 25mm, especially as you've confirmed the main fuse as 60A

 

[Jay Sparks]

How do you know the water and gas needs bonding? Have you tested them?

Jay

 

[shinypen]

Thanks everyone. Plenty for me to think about which is exactly what I need!

My understanding is any incoming metal service pipework needs to be earthed regardless? Incidentally, just found out my friend was charged for the bonding and meter tails upgrade whatever the requirements are!

 

[Des 56]

Thanks everyone. Plenty for me to think about which is exactly what I need!

My understanding is any incoming metal service pipework needs to be earthed regardless? Incidentally, just found out my friend was charged for the bonding and meter tails upgrade whatever the requirements are!

"Bonded" shinypen,Bonded

He was more than likely stung by a not too rare company which has been badged by the naughty Niceic money grabbers
Maybe the type of courses that enable registration these days promotes standards that are questionable all too often

 

[westward10]

Think there will come a time when you are better off using a contractor not in a scheme.

 

[Risteard]

With Amd 3 pfc is calculated as 230 x.95 (Cmin) = 218.5/0.3 = .73 Ka

Cmin isn't factored into PFC measurements. If anything for PFC you would be concerned about Cmax which isn't even defined.

 

[The Ghost]

Cmin isn't factored

Better tell the people who wrote GN3.

• Fault current, I = U0 × Cmin /Zs

where:

U0 is the nominal voltage to Earth,

Cmin is the minimum voltage factor to take account of voltage variations depending on time and place, changing of transformer taps and other considerations.
Pg. 127

 

[Risteard]

Better tell the people who wrote GN3.

I don't have my copy on me at present to verify this, but remember this is only a guide book and does not form part of the Wiring Regulations, and indeed may contain errors!

 

[The Ghost]

@Risteard If you look in the regs at 411.4.5 411.5.4 etc. and onwards you will see Cmin is factored in to Zs x Ia < Uo x Cmin. Although they dont actually give that formula it is clear in BS7671 it is meant to be factored in by impication. btw I quoted the GN3 verbatim and page number. Although I do agree the Cmax factor may be more appropriate as a safety margin.

 

[Richard Burns]

There is a difference between the prospective fault current and the fault current calculated from the I = U0 × Cmin /Zs formula.
In the second case this formula is being used to determine the trip time of a protective device and so should be the lowest value of fault current that may occur on the installation.
Where you are determining the prospective fault current this is to ensure that the protective device an handle this current so you are determining the maximum expected value that may occur on the installation.
Any protective device must be capable of operating quickly enough at the lowest fault current and also capable of withstanding the highest fault current.

 

[Ian1981]

Cmin isn't factored into PFC measurements. If anything for PFC you would be concerned about Cmax which isn't even defined.

Cmax is given a figure of 1.1.
Normally used when you want to calc fault current between phases at design stage.

 

[Risteard]

Cmax is given a figure of 1.1.

Where?

 

[shinypen]

Just as a follow up. Had another look today.

The 3 neutrals in to one were actually as follow: 3 x 1.5mm in to one 2.5mm. The mcb was 6amp so not actually dangerous if a little lazy???

There was definitely no bonding in place even though he'd charged for it and recorded it on the cert. Thanks.

 

[Ian1981]

Where?

Iet 17th edition design guide

 

[Risteard]

Iet 17th edition design guide

Which comes from IEC documents - my point stands that Cmax is not a defined term within BS7671. (I don't believe even the IEC document refers to it by that name.)

 

[Richard Burns]

Cmax is defined in guidance note 6, but not in BS7671, as far as I know; the value of 1.1 (and 0.95) is taken from a cenelec technical report "Determination of cross-sectional area of conductors and selection of protective devices" in 2011.

 

[Ian1981]

Cmax is defined in guidance note 6, but not in BS7671, as far as I know; the value of 1.1 (and 0.95) is taken from a cenelec technical report "Determination of cross-sectional area of conductors and selection of protective devices" in 2011.

It's just 230v x 1.1 is 253v. It's the electricity safety quality and continuity regulations which allow +10% to -6% of 230v
230v +10% is 23v
230+23v is 253v 230x 1.1 =253v
But yeah cmax isn't in bs 7671 unless I've missed it.

 

[goasis]

Despite all the discussion, going back to the op, there def seems to be some issues with the certification,
if the bonding box is ticked, but there isn't any (and they've been charged) that's an issue
I can't see why you wouldn't measure and record a ze.
They obviously haven't done any zs testing either.
Externally at least, the cu sounds like a right lash up.
All makes you wonder what else they have bodged their way through.

 

[Pete999]

Thanks everyone. Plenty for me to think about which is exactly what I need!

My understanding is any incoming metal service pipework needs to be earthed regardless? Incidentally, just found out my friend was charged for the bonding and meter tails upgrade whatever the requirements are!

Bonded not earthed

 

[Strima]

Hopefully it's been sorted now as they've had two years...