Bonding to a lighting conductor

[albi]

Hi Boys andgirls

Does any one have any idea on the size the bonding conductor should be to alighting conductor. Its for a small church, it is a TNS system single phase

Ze 0.40Ώ and PFC0.575KA. The distance from the MET to the lighting conductor would be 60M away.

If I understand this BS7671 states it needs to beearthed. And as I have just changed the DB's in the church I would assume it'sdown to me



The reg's aresaying use the adiabatic equation but what would you use for I[SUP]2 [/SUP]forthe lighting strike[SUP]. [/SUP]

 

[Dean Williams]

i think it needs to be the same size as the rest of the main protective bonding. i.e. the same as your water, gas, oil etc

 

[Farmelectrics]

I always thought it was earth tape for lighting conductors and they were taken down to earth rods that are situated in pots around buildings that's how I remember them

 

[albi]

Yes but they still need to be bonded to the MET as well

 

[netblindpaul]

I thought that lightning work was special?

 

[Deleted member 9648]

It should only be undertaken in conjunction with a lightning conductor engineer....dont do it off your own back.Just note it on your cert that it is not done and that advice on main bonding should be sought from a L/C specialist.

 

[Farmelectrics]

I see albi didn't no it had to be bonded to met in building thought it was just a far date cage effect on building and the strike would just be dispersed down rods wouldn't that bring a high fault path back into building

 

[Air Conditioner]

I am confused, are we talking about lighting:bulb2: or lightning conductors? Hate to sound thick but...................
Agree with post 5 lightning conductors are specialist stuff.

 

[Engineer54]

Am i missing something here, what specialist requirements are there about bonding a lightning protection system to a MET?? The only requirement i would make, is that the connection to the lighting protection system, must be accessible, unless the connection is made by exothermic/braze welding...

You only need specialists to design the overall lightning protection system. You shouldn't even need specialists to install the system, but then that was in the day's when electricians Were real electricians. I wouldn't want any of these 17 day/Electrical Trainee being let loose on an LP installation, not unless they were being closely supervised anyway!!

 

[Deleted member 9648]

Am i missing something here, what specialist requirements are there about bonding a lightning protection system to a MET?? The only requirement i would make, is that the connection to the lighting protection system, must be accessible, unless the connection is made by exothermic/braze welding...

You only need specialists to design the overall lightning protection system. You shouldn't even need specialists to install the system, but then that was in the day's when electricians Were real electricians. I wouldn't want any of these 17 day/Electrical Trainee being let loose on an LP installation, not unless they were being closely supervised anyway!!

The 'regs' clearly state bonding to a lightning conductor should be carried out in accordance with bs 62305.....as this is outside the experience of most electricians it should be left to a specialist.

 

[needasparks]

As others have said it must be bonded to the the MET but it should be checked by Lightning conductor specialist as how does the OP know it is correctly installed and that some pikey has not pinched half of it leaving the installation more dangerous as after bonding.

 

[RISElectrical]

I am not 100% on this and don't have the BS in front of me but under BS 62305:2006 (which only came into practice in around 2009) it requires bonding to the MET however I think under BS 6651 which may be your case they didn't need bonding to the MET

 

[Engineer54]

The 'regs' clearly state bonding to a lightning conductor should be carried out in accordance with bs 62305.....as this is outside the experience of most electricians it should be left to a specialist.

I can't think of any special arrangement that is required by any countries code or regulation regarding bonding a lightning protection system to the MET or it's equivalent... Certainly not to the point of calling in a specialist contractor!!!

 

[RISElectrical]

out of interest I bet nobody here can find me a qualification that (a) proves competency to electrically test a lightning system and (b) one that supersedes an electrical NVQ3 +

Most lightning systems are installed and tested by steeplejacks, qualified to an NVQ2 level

 

[Engineer54]

out of interest I bet nobody here can find me a qualification that (a) proves competency to electrically test a lightning system and (b) one that supersedes an electrical NVQ3 +

Most lightning systems are installed and tested by steeplejacks, qualified to an NVQ2 level

Only when the LP system involves steeples, chimneys or other higher structures with no means of normal access. Normal building LP systems which make up the vast majority of the LP systems installed, are most certainly not installed by steeplejacks, ...they are installed by competent electricians!!