Supp bonding

[m4tty]

Hi,

Being relatively new to the game I wanted to ask about supplimentary bonding. We did brush over the subject in college but certain parts I can get my head around.

What edition of the regs was it where hot and cold pipes were bonded together under sinks etc.

I know supp bonding can be omitted if certain criteria is met re disconeection times and rcds present. So most new work will be covered by rcd so no need to worry about supp bonding if the conditions are met(usually are) but I still want to understand the subject properly.

Is it just belt and braces approach as hot and cold will be connected together at the boiler so why supp bond under sink. Is it incase the continuity is lost somewhere?

Thanks in advance for any help

 

[Brian 157]

Bonding regs have changed a fair bit as you know but the old "join the pipes togther" style was earlier 16th, if memory serves correct it was changed for ammendment 3 (blue book) so that all pipes were bonded to earth terminals of circuits in the bathroom.

 

[Andy™]

iirc, 15th had bonding under kit sink, 16th didnt

 

[m4tty]

Why did they bond the pipes under the sink as they'll be joined at boiler no? And water and gas will also be bonded at met? Just trying to understand the thoughts behind it?

 

[Chr!s]

Matty

Supplementary equipotential bonding was used in locations of increased shock risk in the 16 and is also required in certain installations under the 17th.

It was part of the old eebads which is now ads, it is there to establish a equipotential zone and further reduce touch voltages between exposed and extraneous parts under fault condition.

 

[SLIPSHOD & SLAPDASH]

The 14th edition was the first to bring in supplementary bonding & the 15th ba***sd it all up by almost saying 'if its metal-earth it' Look at an office building from the 80s and you will see earth links across opening windows, handrails on internal staircases etc

---------- AUTO MERGE Post added at 19:09 ---------- Previous post was at 19:06 ----------

Why did they bond the pipes under the sink as they'll be joined at boiler no? And water and gas will also be bonded at met? Just trying to understand the thoughts behind it?

You have to remember that the regs cover from a studio flat up to a multi building factory and the resistance of the pipework can vary, so you bond to make thing of the same potential where the risks may be

 

[Larnacaman]

The 14th edition was the first to bring in supplementary bonding & the 15th ba***sd it all up by almost saying 'if its metal-earth it' Look at an office building from the 80s and you will see earth links across opening windows, handrails on internal staircases etc---------- AUTO MERGE Post added at 19:09 ---------- Previous post was at 19:06 ----------

Were these sizable braided links Slips?? If so the chances are they are part of the buildings lightning protection system. Most of the project buildings i've been involved with of any decent height, have the metallic window frames bonded to the lightning protection.

Never seen stairway handrails bonded though, ...that would have been easier enough to achieve via the stairwell concrete re-bar layout out!!!

 

[SLIPSHOD & SLAPDASH]

I've never seen that. Back in the 15th edition days we had to make up short links and drill and tap the windows to bolt up these links. We never got involved with the lightning protection nor have heard of what you mentioned. We used to think up the most ridiculous things to bond, just cos they were metal, put the idea to the foreman who 99% of the time would ok it.

 

[Larnacaman]

Slip,

Depends a lot on what type of Lightning protection system is being utilised. If cable/tape down conductors are being used, then windows are going to be, in many instances too close to the down conductors and will therefore be bonded to the system. Not so if the down conductor is the steel framework or the buildings re-bar system. Generally these days the later is the case in most office block buildings. Saves an awful lot of money, is mechanically sound and is far more convienient.