eicr

[1983]

Hi all need some advice please got a 16mm twin earth submain in block of flats to flat 1 coming off a 60 amp dp isolator so main earth is 6mm water and gas is bonded to flats met via 6mm what code would I use for eicr? Or should I do the adiabatic calculation first to see if it compiles

 

[malcolmsanford]

You can't use the Adiabiatic for bonding it is only used for sizing protective conductors.

What type of system have you there. If it is TNC-S then it should be 10mm as per reg 544.1.1. But is it designed to an earlier edition, is it TT or TN-S in either of these cases it could be 6mm if your main earthing conductor is 10mm, so there are quite a few options for you.

Basically as it is an EICR I would check that you have continuity with the MET, check if there is any damage as in burning on the terminals. If it is sound and depending on the system you have then a C3

 

[1983]

It's a Tncs system old installation not sure what regs it was installed to at the time the twin and earth is old colours I was going to use the adiabatic equation to see if the main earth which is 6mm is ok no point bonding gas and water with 10mm if the main earth is 6mm is my thinking right? it's a small flat with 4 circuits 1 lighting 1 ring 1cooker and one for boiler no additional work is going to be carried out no rcd was planing to replace mcbs with rcbos.

You can't use the Adiabiatic for bonding it is only used for sizing protective conductors.

What type of system have you there. If it is TNC-S then it should be 10mm as per reg 544.1.1. But is it designed to an earlier edition, is it TT or TN-S in either of these cases it could be 6mm if your main earthing conductor is 10mm, so there are quite a few options for you.

Basically as it is an EICR I would check that you have continuity with the MET, check if there is any damage as in burning on the terminals. If it is sound and depending on the system you have then a C3

 

[malcolmsanford]

Again if there is no obvious damage I would leave it, unless the client has asked you to upgrade the system. What was the EICR for change of occupier?

Again is there a reason you want to change the MCBs to RCBOs. Again I agree it would make the installation safer, but if Zs values are fine then it is not a neccessry change.

 

[1983]

Thanks for your input yes its change of occupier rcbos instead of one rcd to have discrimination have a 230v fan in zone one of bathroom going to replace with 12v fan and put rcbo on that circuit fort I put the rest on rcbo seen as don't the the cable runs plus guess to make it little safer. What would I put in the comments bit on the report not up to current regs but complys with earlier regs seen as not sure when the installation was done?

 

[malcolmsanford]

Does the new EICR have a comments section. I personally would note in section E that the installation was not designed or installed to the current BS7671:2008 amendnet etc etc, but under testing found it to be safe for continued use, and then refer to section K your observations and codes

 

[1983]

Thank you for your help much appreciated so if the adiabatic equation shows 6mm main earth is ok then main bondings 6mm is ok and just code it c3

 

[davesparks]

You can't use the Adiabiatic for bonding it is only used for sizing protective conductors.

What type of system have you there. If it is TNC-S then it should be 10mm as per reg 544.1.1. But is it designed to an earlier edition, is it TT or TN-S in either of these cases it could be 6mm if your main earthing conductor is 10mm, so there are quite a few options for you.

no and no, main bonding is sized according to the size of the earthing conductor which is calculated using the adiabatic equation, therefore the size of main bonding is determined via the adiabatic equation. And the main bond for TNCS does not have to be 10mm, that only applies to PME which is one form of TNCS.

 

[davesparks]

Hi all need some advice please got a 16mm twin earth submain in block of flats to flat 1 coming off a 60 amp dp isolator so main earth is 6mm water and gas is bonded to flats met via 6mm what code would I use for eicr? Or should I do the adiabatic calculation first to see if it compiles

I would be more concerned that there is no OCPD for the submain. Unless of course when you say isolator you actually mean something else?

 

[1983]

Sorry I ment a fused isolator and yes it is a pme

I would be more concerned that there is no OCPD for the submain. Unless of course when you say isolator you actually mean something else?

 

[1983]

It is a tncs pme system so if the adiabatic equation shows main earth is ok there's no need to upgrade main earth which is 6mm at present is that right? Which should mean that 6mm bonding is ok ? C2 or c3?

no and no, main bonding is sized according to the size of the earthing conductor which is calculated using the adiabatic equation, therefore the size of main bonding is determined via the adiabatic equation. And the main bond for TNCS does not have to be 10mm, that only applies to PME which is one form of TNCS.

 

[davesparks]

It is a tncs pme system so if the adiabatic equation shows main earth is ok there's no need to upgrade main earth which is 6mm at present is that right? Which should mean that 6mm bonding is ok ? C2 or c3?

Ok, so being PME the bonding should be sized according to the supply neutral conductor. Chances are in a block of flats that is going to be quite large!

 

[malcolmsanford]

no and no, main bonding is sized according to the size of the earthing conductor which is calculated using the adiabatic equation, therefore the size of main bonding is determined via the adiabatic equation. And the main bond for TNCS does not have to be 10mm, that only applies to PME which is one form of TNCS.

Do you actually read what you write or are you making this up as you go along ..................

I'm still trying to work out the point of your post ............. the Adiabatic is not used to work out the size of a bonding conductor directly, it works out the size of the protective conductor, which can then be related to a bonding conductor, once the main protective conductor is sized in a TN/TT system.

A bonding conductor in a TNC-S is directly related to the size of the supply neutral and can not be worked out by anything so where does the Adiabiatic come in here?

As the Adiabatic can also be used to size Circuit protective conductors I think it is wrong of you to tell someone it can also work out a bonding conductor, because it doesn't and that is poor advice, your basically trying to be smart, don't be with me son because you'll lose. I have yet to do it myself or any design engineer worth his salt work out a bonding conductor using the equation this way, your playing with words!!

As for your quote about PME systems, you know dam well that a PME becomes a TNC-S within the installation and you know as well that table 54.8 relates to a TNC-S why are you always trying to pick an argument, are you worried that people might not think you are any good?

Perhaps you intimidate some on here with smart replies, but son when I hang my overalls up at night they know more about electrics than you .

 

[davesparks]

Do you actually read what you write or are you making this up as you go along ..................

I'm still trying to work out the point of your post ............. the Adiabatic is not used to work out the size of a bonding conductor directly, it works out the size of the protective conductor, which can then be related to a bonding conductor, once the main protective conductor is sized in a TN/TT system.

A bonding conductor in a TNC-S is directly related to the size of the supply neutral and can not be worked out by anything so where does the Adiabiatic come in here?

As the Adiabatic can also be used to size Circuit protective conductors I think it is wrong of you to tell someone it can also work out a bonding conductor, because it doesn't and that is poor advice, your basically trying to be smart, don't be with me son because you'll lose. I have yet to do it myself or any design engineer worth his salt work out a bonding conductor using the equation this way, your playing with words!!

As for your quote about PME systems, you know dam well that a PME becomes a TNC-S within the installation and you know as well that table 54.8 relates to a TNC-S why are you always trying to pick an argument, are you worried that people might not think you are any good?

Perhaps you intimidate some on here with smart replies, but son when I hang my overalls up at night they know more about electrics than you .

The earthing conductor size is calculated by the adiabatic equation. This size is then divided by 2 to get the bonding size.

The bonding in a PME supply is related to the supply neutral, but not all TNCS is PME.

I am not your son! I find it insulting and derogatory that you would call me such. Please don't call me that, or any other derogatory name you can think of.

 

[1983]

So what you lot are saying then the end report is unsatisfactory?? As no additional work is being carried out do I still need to upgrade main earth according to the supply neutral to the block of flats or only to the individual flat? To make it satisfactory and obviously once main earth is worked out main bonding can be as well

 

[malcolmsanford]

So for a TT system that that can if mechanically protected have a main earthing conductor of 2.5mm, no let's be generous say it is not mechanically protected and therefore you work it out by Adiabiatic to be in fact 4mm.................your bonding to your calculation would be what half of 4mm.............

Are you being serious here ....................... or are you going to tell me now that a bonding conductor can not be less than 6mm, so where does the adiabiatic equation come in there

Your just making this up as you go along ..................

 

[1983]

Little update there is a 10mm bonding on gas and water which goes directly to intake met must do had no sigh of it in ccu and no sigh of met in communal cabent where main supply for the flats is. There's a 16mm earth coming to the fused isolator from there a 16mm twin and earth goes to flat and the 6mm earth in the flat is connected to the 16mm earth shall I run a 10mm earth from the isolator to the flats ccu tomake it 16mm? Also I got a reading of 0.07 ohms from the gas and water to the ccu met

 

[Deleted member 26818]

Are the flats part of the overall installation, or separate installations?
If you feel that they are part of the overall installation, then the bonding will have to be sized according to the main incomer.
If you feel that the flats are separate, then the main earth is sized by use of the adiabatic equation.
If the 6mm is adequate as per the adiabatic equation, and there are no visible signs of deterioration or heat damage, then a code C3 would to my mind be applicable.

Love the way that in one post the bonding is sized by use of the adiabatic equation, then in another it is sized according to the supply neutral.

 

[1983]

Thank you for your feedback appreciated I guess there all separate as each flat got there own meters own fused isolators but all bonded back to the main met. Can't take a ze reading as can't disconnect main earth got a good zs reading from submain flats ccu. pfc was 1.5 something ka no sign of heat damage on 6mm at ccu.gaz and water bonded back to main met at communal cabinet somewhere no sight of it got 0.07ohms reading from water and gas to flats ccu met even tho it doesn't go there.

Are the flats part of the overall installation, or separate installations?
If you feel that they are part of the overall installation, then the bonding will have to be sized according to the main incomer.
If you feel that the flats are separate, then the main earth is sized by use of the adiabatic equation.
If the 6mm is adequate as per the adiabatic equation, and there are no visible signs of deterioration or heat damage, then a code C3 would to my mind be applicable.

Love the way that in one post the bonding is sized by use of the adiabatic equation, then in another it is sized according to the supply neutral.

 

[rattlehead85]

The earthing conductor in a tn-c-s should be as a minimum equally sized with the protective bonding conductors which are sized in relation to the neutral of the supply.
Minimum sizing of earthing and bonding in a TN-C-S is 10mm2 END OF!!