What exactly can an 'domestic installer' do?

[steptoe]

the protective conductor of his network for connection to the protective conductor of the consumer's installation.

this can be TERRA

as in Terra Terra can it not.?

 

[Andy™]

that shouldnt be an issue, after all on TNS its 0.8,or on TT it can be a LOT LOT more, its about how you can also prove compliance outside 7671,

I have often had TNCS >0.35 and simply noted on my cert and used some other means of proving disconnection times.

depends on what you plan to power with it... for domestic, rarely a problem, but if you have some D breakers for various stuff (more commercial use here), Zs may need to be lower than the max Ze for TNS

 

[Andy™]

the protective conductor of his network for connection to the protective conductor of the consumer's installation.this can be TERRA

as in Terra Terra can it not.?

this would be TN-S, like if it was a lead sheathed, or split con. not TT

 

[steptoe]

depends on what you plan to power with it... for domestic, rarely a problem, but if you have some D breakers for various stuff (more commercial use here), Zs may need to be lower than the max Ze for TNS

yes agreed,

I done an industrial unit a few years ago and the laser cutter required a Zs of <0.05

the local DNO had to bring in a totally separate earth to the install(at customers expense tho!)

 

[Andy™]

yes agreed,I done an industrial unit a few years ago and the laser cutter required a Zs of <0.05

the local DNO had to bring in a totally separate earth to the install(at customers expense tho!)

bet that once would have been expensive! what protection did you install for it?

 

[steptoe]

the protective conductor of his network

the star point of the network is always connected to earth (Terra) is it not?

 

[Andy™]

the protective conductor of his networkthe star point of the network is always connected to earth (Terra) is it not?

yes, but the DNO dont 'provide' TT to the property, that part is on customer if req'd. they can only provide TNS of TNCS to property

 

[steptoe]

bet that once would have been expensive! what protection did you install for it?

200A HRC,

it wouldnt run on an MCB of any sort,(alledgedly)

so I provided the circuit according to the manufacturers instructions,(ala BS7671).

wired in about 10m of SWA from DB to an isolator, then straight to machine stop box.

 

[green-hornet]

I am really pleased that this topic has come about and that we are now having the debate.

Often earthing arrangements are taken for granted, its only when you see the implications that as an electrician you improve your ability to provide a safe electrical installation.

I have never liked TNC-S or PME for the reasons often mentioned on this forum.

Its the one single earthing arrangement open to such widespread abuse.

Posters who have pointed out the requirements or obligation of the dno's to provide an earth are correct.

However there is a clause in their contract that gives them the right to withdraw any earthing arrangement if it is found that the arrangements can not comply with the regulations.

Unfortunately I have found that it has been left to competant electricians to find the faults and report them for any action to be taken.

For instance how many properties do you still find that have a nuetral fuse?

They will only change them when you report them.

Keep it safe keep it real and lets debate a little more I love it!

 

[Andy™]

PME was brought about because its one less connection in the network for them to install, and they only need 2 core cable so more cost savings there. but if it fails, there is no back up. as well as all the dangers of exporting it etc.

another example of money over safety

came accross plenty fused neutrals... usually very obvious by looking at the service head, but how many 5 day wonders would even know what to look for? (or even understand the problems with fused neutral or PME?)

 

[steptoe]

I am really pleased that this topic has come about and that we are now having the debate.Often earthing arrangements are taken for granted, its only when you see the implications that as an electrician you improve your ability to provide a safe electrical installation.

I have never liked TNC-S or PME for the reasons often mentioned on this forum.

Its the one single earthing arrangement open to such widespread abuse.

Posters who have pointed out the requirements or obligation of the dno's to provide an earth are correct.

However there is a clause in their contract that gives them the right to withdraw any earthing arrangement if it is found that the arrangements can not comply with the regulations.

Unfortunately I have found that it has been left to competant electricians to find the faults and report them for any action to be taken.

For instance how many properties do you still find that have a nuetral fuse?

They will only change them when you report them.

Keep it safe keep it real and lets debate a little more I love it!

debate, who said anything about a debate,?!

its a great big bloody arguement I want.!!!

 

[steptoe]

PME was brought about because its one less connection in the network for them to install, and they only need 2 core cable so more cost savings there. but if it fails, there is no back up. as well as all the dangers of exporting it etc. another example of money over safety

came accross plenty fused neutrals... usually very obvious by looking at the service head, but how many 5 day wonders would even know what to look for? (or even understand the problems with fused neutral or PME?)

I think most people on here will know my views on both subjects raised here.

 

[green-hornet]

I think me and Steps would like everything TT.

BRING ON THE REVOLUTION

 

[Andy™]

I think me and Steps would like everything TT.BRING ON THE REVOLUTION

you can add me to that too!

 

[green-hornet]

OMG are we the inner circle?

 

[Andy™]

OMG are we the inner circle?

Were more than just the 'inner circle'

 

[jl-heating]

do u have a special handshake yet ?

 

[Apache]

do u have a special handshake yet ?

Can I suggest a logo?

you could put it on your vans...........

 

[SPECIAL LOCATION]

it says (4) Unless he can reasonably conclude that it is inappropriate for reasons of safety, a distributor shall, when providing a new connection at low voltage, make available his supply neutral conductor or, if appropriate, the protective conductor of his network for connection to the protective conductor of the consumer's installation.

but it also says elsewhere that PME cannot be used in certain conditions (like the caravans you mentioned), but incoming supply to site can be PME and so can certain buildings

Just to point out here the word "REASONABLY" is a great big get out clause for a whole box full of options where various bodies decide they cannot or don't want to meet certain contractual obligations.!

it normally means..

we will try and do this.. but if its too much hassle tough! :|

 

[steptoe]

do u have a special handshake yet ?

ooohhhh

by the square by the level by the plumb,,,,,,,

sorry, wrong club,

by the spike,

by the grid ,

by the resistance of the earth,,,,,,

I like this rolled up trouser leg malarkey........