DB REPLACEMENT ON TT SYSTEM

[sherman0251]

Hi Guys

Im replacing a DB in a domestic property with a TT Supply. Never done much with TT systems before. Am i ok just fitting a stand split cu with 2 x 30mA RCDS or do i need to also fit a 100mA RCD before the cu too?

Any help appreciated?

 

[RF Lighting]

A dual split will be ok as long as the board is NOT metal clad.

 

[PrenticeBoyofDerry]

As above, providing all circuits are covered with 30mA RCD protection, you are okay.

 

[sherman0251]

Can i ask why re the metal clad? Might be a stupid question!

 

[PrenticeBoyofDerry]

The RCD should be in an insulated enclosure and also because of poor earth, if tails should become loose and contact the metal box.

 

[riveralt]

I know we all have to learn but this and your previous question on RCD fault finding is pretty basic stuff.
As you are offering customers a service shouldn't you be directing your questions to your competent scheme helpline?

 

[sherman0251]

Thanks for your replies, i know how to fault find but just always seems a laborious task of inspecting for a earth fault. Just wondered if there was any handy tips that others had to speed things up? With regards to the TT questions i have never had to replace a cu on TT supply before and thought id ask you guys!

 

[ricicle]

You can use an insulated unit with the dual RCD set-up or a metal clad unit if you include a time delayed RCD in an insulated enclosure in the tails before the unit.
My electrician mate's NIC inspector would not accept the tails between the meter and CU being non-RCD protected on a TT system (I know, I know !!) so wanted a TD RCD as close to the meter as possible.....

 

[JohnW2]

The RCD should be in an insulated enclosure and also because of poor earth, if tails should become loose and contact the metal box.

Of course, even with an insulated CU (and no other upstream RCD), it's theoretically possible for the tails to become lose and come in contact with the (usually unprotected) earth bar of the CU - so even that is not 'foolproof'!

Kind Regards, John

 

[securespark]

The 15th used to say that you could use a metalclad on TT if you used specially designed grommets to separate the tails from the enclosure...

Again, this would not stop contact inside the board!

 

[ban-all-sheds]

I know we all have to learn but this and your previous question on RCD fault finding is pretty basic stuff.
As you are offering customers a service shouldn't you be directing your questions to your competent scheme helpline?

Trying to do an insulation test on my ring main! As it is not feasable to dissconnect all appliances from sockets, I have connected the phase and neutral together then testing them to earth. For some reason it wont let me! It wont even let me test between cpc and neutral. Any ideas!
Im new to testing just about to take my 2391 inspect and test!

I have just done the 17th edition course last week and sat the exam on thurs!

I am a spark myself

Im a qualified spark to 17th edition just never filled out [an EIC] before!

Etc, etc, etc...


He's been asking here how to do his job for 5 years.

 

[knowall]

Sad not the OP

NA

 

[ban-all-sheds]

I expect his customers are.

 

[sherman0251]

Thanks for all your help guys! Appreciate it!

 

[riveralt]

I know we all have to learn but this and your previous question on RCD fault finding is pretty basic stuff.
As you are offering customers a service shouldn't you be directing your questions to your competent scheme helpline?

I take it from your lack of reply you are not a member of a competent persons scheme.
On that basis I just wonder what have you told your customer regarding registering the work you are conducting (fitting a new consumer unit) with the Local Authority Building Control?
Are you going to register it - application must be done before you start?
Or are you going to commit a criminal offence by carrying on without registering the work?