Dodgy Work

[ElectekAir]

Just been asked to go look at a job that some other spark has done (replacing CU) and a few other things

Builder called because spark left a socket face off the wall and was not really happy with the general feel of things (bloke used a socket and see to test)

Removed cover of CU no bonding, 2.5mm main earth, all sleeving in CU still green, no grommets on any accessories, no earth provided at cutout.

No certs yet the company is also part p registered:red card

Will take some pics later as i am going to do a full test just to check

 

[Andy™]

wouldnt like to see his other jobs

 

[AndyD1]

bad day explodebad day explode Look for the smoke

 

[Lee321]

dam that sounds real bad

 

[ElectekAir]

According to the regs what is the minimum size of the main earthing conductor allowed on a TT system?

Just called elecsa (whome this contractor is registered with) who told me to check the regs because acording to them 2.5mm is ok for a tt system

Called NIC and they said acording to 7671 10mm

 

[Andy™]

2.5 if mechanically protected. 4 if not

 

[Lee321]

good Q.

54.1 is for buried which might not be the case so then what in that situ?

 

[Lee321]

[quote name='Andy

 

[Andy™]

im sure thats for rods. dont have regs here to check it though

 

[Lee321]

ah yes 542.3.1 refers to 543 . then 543 (ii) refers to 543.1.4 = table 54.7

i think. so should equal the line csa upto 35mm then its half. thats what i get atm

in addition to what you said min 2.5 protected and 4 if not

it sounds wrong tho

 

[Lee321]

osg says 4mm or 2.5 if protected from MD

quite bizarre how osg has a table that the brb doesn't

obviously the table is mostly made up of the figures given in brb but i cannot find the specific tt scenario in brb

 

[ElectekAir]

But now is burried in the fabric of the building concidered mech protection?

 

[Lee321]

edit: the books appear to say if mechanically protected buried or not buried indicating MP is another method other than the actual burieing (possibly the sheathing)

2.5 is a puffs size tho. most of us just wouldn't even if allowed don't you think?

 

[ianmacd]

I believe the BRB leaves it as an exercise for the reader to calc the minimum size needed.

 

[Lee321]

I believe the BRB leaves it as an exercise for the reader to calc the minimum size needed.

or use table 54.7 ian ? 543.1.1 (ii) ??

 

[Andy™]

[quote name='Lee

 

[ianmacd]

[quote name='Lee

 

[Lee321]

Indeed but for TT the fault current is likely to be low compared to a TN system.

yes totally ian. just trying to find where they say x for tncs etc earthing arrangements and x for tt ?

 

[ianmacd]

Not sure they did. They just give a table for us lazy *******s.