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E

egg661

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i have a TT system in a sorry state. please could you advise on these points

1.The earth cpc has snapped off the earth rod and is to short to reconnect Its is 2.5 csa. What is the required csa for the main earth 10mm or 16mm

2. there does not appear any bonding on the incoming gas supply. What is the csa required 6mm?

3. the consumer unit is rewireable type protected by a RCD (no sure if its 100ma) between consumer unit and incoming supply. 1 lighting circuit, 2 ring, 1 heating and electric cooker

what protection do i need in the new CU and should i remove the old RCD before the CU
thanks in advance
Mark
 
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i have a TT system in a sorry state. please could you advise on these points

1.The earth cpc has snapped off the earth rod and is to short to reconnect Its is 2.5 csa. What is the required csa for the main earth 10mm or 16mm

2. there does not appear any bonding on the incoming gas supply. What is the csa required 6mm?

3. the consumer unit is rewireable type protected by a RCD (no sure if its 100ma) between consumer unit and incoming supply. 1 lighting circuit, 2 ring, 1 heating and electric cooker

what protection do i need in the new CU and should i remove the old RCD before the CU
thanks in advance
Mark
hi mark,
looking at the questions you have asked i would employ the services of a local part p registered spark ;)
 
E

egg661

  • Thread Starter Thread Starter
  • #3
hi mark,
looking at the questions you have asked i would employ the services of a local part p registered spark ;)
Thanks for the reply. I am fully quilfied but have not worked in the Industry for over 10 years. So as the old gray matter is a bit rusty just woundered if someone can refresh me as did not have much to do with TT in my practicing years. Also now is 17th edition

regards mark
 
S

Spudnik

  • Thread Starter Thread Starter
  • #4
Hi Mark,

A fair bit has changed over the years and its not something easily put across on a forum!

If you are thinking of getting back into it, it may pay you to sit the update course and get registered as this work would need notifying to your LABC.

A copy of the current 7671 along with the OSG would give you all the info needed.

However, a number of factors would dictate main earthing and bonding sizes which would need to be measured and calculated.

Normally 10mm main earth is fine along with 6mm for main bonding to gas and water, assuming no mechanical protection and test results permitting.

New CU should be dual RCD with not necessarily a stand alone RCD upfront as in days of old, providing your new CU is all insulated and of class II construction.
 
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hi again mark,
what jason has said is spot on. things have changed a bit and this work would need either notifying through labc or you would need to employ a part p registered spark.
all the best ;)
 

scotsparky

-
Arms
i have a TT system in a sorry state. please could you advise on these points

1.The earth cpc has snapped off the earth rod and is to short to reconnect Its is 2.5 csa. What is the required csa for the main earth 10mm or 16mm

2. there does not appear any bonding on the incoming gas supply. What is the csa required 6mm?

3. the consumer unit is rewireable type protected by a RCD (no sure if its 100ma) between consumer unit and incoming supply. 1 lighting circuit, 2 ring, 1 heating and electric cooker

what protection do i need in the new CU and should i remove the old RCD before the CU
thanks in advance
Mark
Hi mate you didnt state the incomming cable size. The Main Earthing can be worked out in 2 ways. Either by looking at Table 54.7 of the 17th edition or by using the Adiobatic. If your nos sure how to work the adiobatic use the tables is may be overkill but at least your covered.



The Gas ,Water,Structural steel has to have a main earth bond in place of at least 10mm Look at Table 54.8 for sizes.

As for changing the CU get someone whos part P qualified. I am in Scotland and not sure of part P so cant help you there. If your not fully qualified dont touch! The Rcds for the final circuits should be 30ma but if a new CU is getting fitted then it will be sorted then.
 
E

egg661

  • Thread Starter Thread Starter
  • #7
Hi Mark,

A fair bit has changed over the years and its not something easily put across on a forum!

If you are thinking of getting back into it, it may pay you to sit the update course and get registered as this work would need notifying to your LABC.

A copy of the current 7671 along with the OSG would give you all the info needed.

However, a number of factors would dictate main earthing and bonding sizes which would need to be measured and calculated.

Normally 10mm main earth is fine along with 6mm for main bonding to gas and water, assuming no mechanical protection and test results permitting.

New CU should be dual RCD with not necessarily a stand alone RCD upfront as in days of old, providing your new CU is all insulated and of class II construction.
Thanks Jason

So just a standard split load CU with 30ma for socket protection would meet current regulations
regards Mark
 
S

Spudnik

  • Thread Starter Thread Starter
  • #8
Thanks Jason

So just a standard split load CU with 30ma for socket protection would meet current regulations
regards Mark
Nooooo.

ALL circuits must now be 30mA RCD protected, hence the dual RCD CU.
 
E

egg661

  • Thread Starter Thread Starter
  • #9
Nooooo.

ALL circuits must now be 30mA RCD protected, hence the dual RCD CU.

Lol any reccomendations on a suitable CU then
 

scotsparky

-
Arms
Usee a small Merlin type 9 with 30ma Modular RCBOs on all circuits. 100A main isolator sorted (may be expensive:()
 
S

Spudnik

  • Thread Starter Thread Starter
  • #11
Usee a small Merlin type 9 with 30ma Modular RCBOs on all circuits. 100A main isolator sorted (may be expensive:()
I bet it will be:D

Prices vary a fair bit, depending on make etc.

You are probably looking around £100+ fully loaded.

Pop into your local wholesalers.

They normally have specials on.:)
 

scotsparky

-
Arms
I know it will be but if all circuits are on seperate RCBOs no worries Get bonding,Suplimentaryin place and your laughing :D
 
D

DHES-LTD

  • Thread Starter Thread Starter
  • #13
Proteus 17th edition split load board + 10 MCB'S £65 + Vat at CEF.
 

scotsparky

-
Arms
Speak to a wholesaler such as Newy& ayre, Edmonsons, City Electric, Electric centre and tell them what you need and they will get it for you. Dont accept the first price unless you are possitive its a good one
 

Des 56

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Arms
Esteemed
If your installation is in a sorry state, be aware that the lighting circuits, if they are up and down, woulld ideally be on seperate rcds This may become a problem with imbalance of the rcds if there is a shared neutral
Just a word of caution not to have to sudenly come up against this problem when changing consumer unit
 

scotsparky

-
Arms
Thats why where possible i like to put in rcbo modules
 
S

spark1

  • Thread Starter Thread Starter
  • #19
6mm2 is the minimum size for the main protective equipotential bonding to the Gas service pipework on a TT system..although this only usully applies if the Main Earthing conductor is no more than 10mm2,,,,,,,on TNCs supplies the minimum bond is 10mm2
 
K

kung

  • Thread Starter Thread Starter
  • #20
Lots of deals on CU's eg screwfix do a 10way split rcd wylex for £97.86 inc free x5 pendants & x10 dbl sockets.
Regards
Kung
 
E

egg661

  • Thread Starter Thread Starter
  • #21
Thanks for all your replys . I have purchased a 17th edition dual rcd CU today.

I have run the main earth to the earth rod , run the main equipotential. Floor boards up every where lol.

Had a look and the old CU and notocied that the lighting circuits still wired in old rubber cables :eek:
Thought thats strange as changed a few light fittings and never noticed them before.
checked all light fittings and their wired in T& E and all the switch wires are as well except for the one in my bedroom which is rubber.

Some ones been very naughty:mad: i will have to pull up a few more floor boards and find were its joined. Oh and looks like a bit of chasing out and replacing that switch wire.

I'am so lucky didn't want to put my feet up any way.:)

Mark
 
S

Spudnik

  • Thread Starter Thread Starter
  • #22
Hi Mark,

That old rubber cable needs to come out, as you are doing.

Perfectly fine in its day but it would have aged and will be starting to break down.

That would give your IR test some hell:D
 
G

Guest123

  • Thread Starter Thread Starter
  • #23
100% need to get rid of that rubber cableing mate ASAP!!!;)
 
E

egg661

  • Thread Starter Thread Starter
  • #24
Hi Mark,

That old rubber cable needs to come out, as you are doing.

Perfectly fine in its day but it would have aged and will be starting to break down.

That would give your IR test some hell:D
Not half its alreading crumbling at the CU
 
S

Spudnik

  • Thread Starter Thread Starter
  • #26
They're actually ok, apparently made by wylex.
Im only kidding mate.

Trouble is, i get very frustrated fitting the cheaper units, as they can be fairly flimsy.

I have just for the first time, fitted a new GE CU and it had a plastic DIN rail!!!:eek:
 
M

Mac

  • Thread Starter Thread Starter
  • #27
Always use Hager,you can't go wrong with them:D
 
S

Spudnik

  • Thread Starter Thread Starter
  • #28
Always use Hager,you can't go wrong with them:D
Always do usually, but space was a bit tight so had to install a smaller unit and it was all they had.

Never again tho.
 
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R

riduan

  • Thread Starter Thread Starter
  • #29
Hi all,
I am new at this forum
Can u all help me to solve one problem
 
G

Guest123

  • Thread Starter Thread Starter
  • #30
Hi all,
I am new at this forum
Can u all help me to solve one problem
Hi Riduan, welcome to the forums.

Best thing to do is start a new thread in the relevant forum.;)
 
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