Supplementary bonding requirements

[Pretty Mouth]

Evening All. I've been having a debate (argument) on a FB group with another well respected spark, and my old tutor. The subject of discussion - supplementary bonding.

Their opinion is that it is required throughout an installation, where ever the conditions in 415.2.2 cannot be met without it. My conflicting opinion is that it is not required throughout an installation, but is only required in certain locations or under certain circumstances. I based this opinion on the following regs:

410.3.2
Additional protection is specified as part of a protective measure under certain conditions of external influence and in certain special locations (see the corresponding sections of Part 7).

415 ADDITIONAL PROTECTION
Note Additional protection in accordance with Section 415 may be specified with the protective measure. In particular, additional protection may be required with the protective measure under certain conditions of external influence and in certain special locations (see the corresponding section of Part 7).

The protective measure generally being ADS, if supplementary bonding was required throughout I would expect it to be stated so in 411 (Protective Measure: Automatic Disconnection Of Supply). There is no mention of sup bonding in 411 at all. I have found it is required where disconnection times cannot be met (419.3), static converters (551.4.3.3), whatever they are, and various special locations in part 7 eg. bathrooms. I cannot find any other requirements for it.

The argument has been going on for a few days now, and although unable to show me regulations to back their opinion up, they are adamant that they are correct, so much so that I'm beginning to doubt myself (again). Please could somebody put me straight on this.

 

[Mark Wright]

throughout, like bedrooms etc?

OSG 4.6 - 4.7 says something like where disconnection times can't be archived and locations etc falling under part 7 BS 7671

it also lists stuff like kitchen sinks and pipes not needing bonding but under 16th these still might have needed bonding?you often see examples from 16th era someone touching faulty kettle and bonded/not bonded pipe/tape etc

 

[Pretty Mouth]

throughout, like bedrooms etc?

OSG 4.6 - 4.7 says something like where disconnection times can't be archived and locations etc falling under part 7 BS 7671

it also lists stuff like kitchen sinks and pipes not needing bonding but under 16th these still might have needed bonding?you often see examples from 16th era someone touching faulty kettle and bonded/not bonded pipe/tape etc

Yeah, that's what they are saying. Bedrooms, living rooms, kitchens, offices, anywhere that that R <= 50V/Ia

 

[Ian1981]

It’s in section 419 where ADS can’t be achieved, it is only the circuit or circuits involved and their location along with any extraneous and exposed conductive parts that need supplementary bonding. Why would you carry this out throughout an installation that is Not in your immediate proximity and were other circuits have effective ADS?

 

[Wilko]

Hi - at the start of Section 415 Additional Protection it states it “may be specified with the protective measure”. Not “shall be specified ...”.

So as I see it, it’s required where Regs call for it. And that’s Special Locations with increased shock risk and where ADS times can’t be achieved as per Reg 419.3 in BBB, AFAIK.

 

[Vortigern]

Amazing this thread, since the '80s this question has been going on and the arguments and confusion are still the same. Nothing new under the sun eh? You often see on sites the over the top bonding and cross bonding confusion, to achieve the then equipotential bonding zone. Essentially if it was metal it was almost superstitious, bond it! Radiators bonded, I still have the radiator bonding clamps, think you can still get them. I have always thought there really needs to be some simple clarification that anyone can understand. Maybe pictures would do it so that there is no more argument and dangerous bonding, where you introduce a potential to metal parts that don't need bonding. Why the hell is the subject so difficult!

 

[Pretty Mouth]

Thanks all for the replies. That confirms my understanding of the matter, and it's nice knowing that I'm not going mad after all.

@Vortigern funny you should mention radiators, it was that that started the argument in the first place. Someone had radiators fed from plastic pipes, with copper tails above the floor, he asked if they needed bonding. I told him no, and it all kicked off from there.

 

[Vortigern]

radiators,

Yes that is common, as people think the water in the pipes will carry the voltage/current to the radiator which is not true.

 

[nicebutdim]

Yes that is common, as people think the water in the pipes will carry the voltage/current to the radiator which is not true.

The inimitable John Ward conducted a couple of experiments to settle this very argument - might be of use to the OP in countering the arguments that led to his current predicament.

View: https://youtu.be/3-3M3r69pOQ

View: https://youtu.be/MF9DCNkaE8I


Apologies for gratuitously posting JW videos, but I could watch them all day - reminds me of Open University programming from my childhood.

 

[pc1966]

In the stuff I'm working on just now there is a lot of extra bonding of metalwork but it is really about EMC control, not being needed to meet ADS as that is fine with the usual CPC provision.

As covered above, only a few aspects of most installations need it.

 

[Pretty Mouth]

Thanks guys, I'm pretty happy with this now. Cheers