Equipotential Bonding

Irish Traveling

Hi All,

It's been over 10 years since I wired a house but I'm currently renovating my own place and have a query around equipotential bonding.

Water pipes are nonmetallic as are all the heating pipework with the exception of the pipes in and around the water cylinder. This pipe work is copper. The copper is only within the plant room, all pipework entering and leaving is nonmetallic.


What are the bonding requirements here?

Any advice appreciated.

Thanks.

D.

Tuco88

I'd run in a main bonding conductor(10mm2) to the water cylinder usually attach it to the c.w feed pipe. Then cross bond to the h.w pipe/heating loop or anything your not happy with. It's been a while sence I wired a house also ha, if I'm wrong I'm sure some one will correct me.

Remember if you have a gas boiler to run a main bonding conductor to that also.

Risteard81

Work should be carried out by a Registered Electrical Contractor (REC).

Is the pipework extraneous?

Stoner

Risteard81 wrote:

Work should be carried out by a Registered Electrical Contractor (REC).

Risteard81.
This is in the charter. There is no need to repeat it. This was discussed with you already.

Risteard81

Stoner wrote: »

Risteard81 wrote:

Work should be carried out by a Registered Electrical Contractor (REC).

Risteard81.
This is in the charter. There is no need to repeat it. This was discussed with you already.

It is a fact which I have every right (in fact a duty) to point out. I answered the OP and I expect you to stop criticising me for pointing out what is a legal reality. You are free to disagree with that reality, but you certainly cannot deny that it is indeed a reality.

Irish Traveling

Risteard81 wrote: »

Work should be carried out by a Registered Electrical Contractor (REC).

Is the pipework extraneous?

I'm aware that work has to be carried out by a REC but that has nothing to do with my query!

My query references the fact that there is extraneous pipework.....so why ask?

Risteard81

Irish Traveling wrote: »

My query references the fact that there is extraneous pipework.....so why ask?

No it doesn't. You simply told us that there was pipework. You haven't told us whether it is actually extraneous or not.

Stoner

Risteard81 wrote:

It is a fact which I have every right (in fact a duty) to point out. I answered the OP and I expect you to stop criticising me for pointing out what is a legal reality. You are free to disagree with that reality, but you certainly cannot deny that it is indeed a reality.

You did not answer the OPs question you asked a question. The OP learned nothing from your contribution over and above you highlighting a fact that we have addressed in the forum charter already.

I have not disagreed with any reality. I've explained to you that "reality" is addressed in the charter. We consider how we have addressed the issue in the charter as satisfactory. We've asked you stop pointing it out alone, it's unnecessary. Once again we are not disagreeing with the text, rule or law. It's the repeated use in posts while offering little advice that we aim to prevent. You can highlight the requirement as part of a meaningful attempt to contribute to answer the question if applicable.

Do not confuse our position on uninformative posts with disagreement with reality, we are aware of the situation, the charter reflects that awareness.

There are many site rules, they are covered in the charters and general site conditions. This rule is given particular attention in the charter for this forum.

You are also expected to follow the charter and the site rules before posting here along with everyone else, and to follow the mechanisms provided to you to challenge same. Arguing with moderators within posts is not one of those mechanisms.

If you have an issue with how I've addressed this or any of your posts, please take it to a CMOD and make your case about what you expect of me and what I'm free to do, you are entitled to an opinion on both, I'll take their direction as I always have.

However please do not continue with this conversation here, this is a direct request. By all means take this up the line, that's not a challenge to you, you are a helpful poster and valuable to the forum.
We are capable and willing to change our approach to posts, but we've made the position to you very clear, possibly you don't like that position and consider the consistency that the mods here are trying to apply to the subject as criticism. We are attempting to provide direction.
We will continue to be consistent in our approach to uninformative posts, so expect the same approach if you continue to produce them.
We will continue along these lines unless directed otherwise.
This in a recurring issue, it's wasting your time and ours consistently talking about it, it's derailing threads. So please either follow the site protocol, elevate your concerns up the line, but don't post on this thread again on this issue.
You have just as much access to the disputes resolution process as anyone else. I'll stand corrected by any findings.
Please don't leave me in a position where I have to take action, I've explained your options to you before. Please take this issue off this thread.

Irish Traveling

Risteard81 wrote: »

No it doesn't. You simply told us that there was pipework. You haven't told us whether it is actually extraneous or not.

Extraneous-conductive-part: A conductive part liable to introduce a potential, generally earth potential, and not forming part of the electrical installation.

E.g copper heating pipework. Read my post again.....

K.Flyer

Irish Traveling wrote: »

Extraneous-conductive-part: A conductive part liable to introduce a potential, generally earth potential, and not forming part of the electrical installation.

E.g copper heating pipework. Read my post again.....

From an RGI perspective..

When we install new boilers we have to follow the regs set out in is813 (2014), so hopefully the following diagrams will be of some help.

Risteard81

Irish Traveling wrote: »

Extraneous-conductive-part: A conductive part liable to introduce a potential, generally earth potential, and not forming part of the electrical installation.

E.g copper heating pipework. Read my post again.....

Indeed. But as you have told us that it is an isolated section of copper pipework I have no reason to believe that it is likely to introduce a potential (probably Earth potential) into the installation.

Have you tried insulation testing between the pipework and the Main Earthing Terminal ensuring that any associated circuit protective conductors are disconnected?

Just because it is a conductive part doesn't mean that it is an extraneous conductive part.

2011

Irish Traveling wrote: »

What are the bonding requirements here?

It is extraneous metalwork.
As such it should be bonded as shown in post #10.

Best of luck with it.

Risteard81

2011 wrote: »

It is extraneous metalwork.

How do you know?

2011

Risteard81 wrote: »

How do you know?

You are correct, I don't know it, I feel jumped the gun a bit on this one.
I have an "industrial electrical installation mindset"

I always go back to basics when considering earthing and bonding:

1) Electrical current (or voltage) flows through the path of least resistance.

2) Electricity can only flow where there is a path through which it returns to the source.

3) When parallel paths are present, flow shall be through all paths. Greater flow will be through the paths of least resistance.

In simple terms: By electrically connecting conductive parts together with a 10 sq. they can be kept at the same potential. If there is no potential difference between two points then a person touching both points at the same time will not have a current flow through them.


If a hot water tank were no be considered (for whatever reason) not be be an extraneous conductive part (so not bonded) in the event of a live conductor making contact with it the tank would rise to the same potential as that conductor without the associated protective device operating. So where could that live conductor come from? Well the modern hot press can have many sources of live conductors such as immersion, zone valves, light, shower pump, solar panel controls, stats etc. However if the tank was connected to the MET and equipotential bonding was installed the associated protective device(s) (MCB, RCD, RCBO) should operate.


I was just reading an interesting ECSSA article on this that supports the view of not bonding under certain circumstances.


The NICEIC (the UK’s regulatory body for the electrical contracting industry) have an interesting way of determining whether something is an extraneous part or not. This text is from their newsletter:

"The metallic part can be assumed not to be an extraneous-conductive-part if the following condition is met:
Rcp> (Uo/Ib) - Ztl
where,
Rcp is the resistance between the conductive part and the MET in ohms
Uo is the nominal voltage to Earth in volts
Ib is the value of current through the body in amperes that should not be exceeded. (The value may be taken as 30 mA for a disconnection time of up to 0.4 s, as given in DD IEC/TS 60479)
Ztl is the impedance of the human body in ohms. The value suggested in DD IEC/TS 60479 is 1000 ohms where Uo is 230 V (50 Hz) under dry or wet conditions.
Taking Ib as 30 mA and Ztl as 1000 ohms (as suggested above where the disconnection times in the installation are 0.4 s or less and Uo is 230 V), the limiting value of Rcp is given by:

Rcp > (230/0.03) - 1000
Rcp > 6667ohms

Thus, if Rcp exceeds 6, 667 ohms, the pipe may be considered not to be an extraneous-conductive-part, such that main bonding of the pipe is not required".

Risteard81

Indeed. I am an NICEIC Approved Contractor as well as a RECI member and IET Wiring Regulations have recognised increased risk in bonding non-extraneous parts by providing an Earth path where it otherwise does not exist. So all very interesting but of course we are dealing with ETCI Wiring Rules here.

But if I was testing to the MET I would base my calculations on the perception threshold.

2011

Risteard81 wrote: »

So all very interesting but of course we are dealing with ETCI Wiring Rules here.

The ETCI is referred to in my ECSSA link.

But if I was testing to the MET I would base my calculations on the perception threshold.

In the absence of a specific ETCI threshold it I would consider that a reasonable course of action for domestic installations in the ROI. I feel that the latest edition of ET101 has put more onus on the designer / electrician.

Irish Traveling

Folks,

Thanks for all the responses. A bit of food for thought. I'll measure the Rcp and see what result I get.

D.

2011

Irish Traveling wrote: »

Folks,

Thanks for all the responses. A bit of food for thought. I'll measure the Rcp and see what result I get.

D.

If I were doing this I would wire a 10 sq. to the hot press regardless of the resistance reading. Following testing I would decide whether to connect it or not. If the reading between the MET is > 6667 ohms (with immersion earth disconnected) then I wouldn't connect. The advantage of having the cable available in an installation that is does not have an extraneous conductive tank is that in the event of the plumbing system being changed (by the addition of solar panels for example) an earth is available if deemed necessary without pulling the house apart.