Main Protective Bonding

[FABElectrical]

Evening all,

Recently started working for a company carrying out electrical installations - I've found a job today that didn't have any bonding to the incoming water or gas supplies and both were in metal so do require bonding.

Spoke with my boss to explain and said that I was popping out to get 10mm2 Green/Yellow, clamps etc and he said not to carry on with anymore works and leave the job; I explained that the actual works to carry out the bonding was easy, would take around 15-20mins to complete, need around 10M of cable and 2x clamps so wouldn't cost a lot and then I can complete the install but his response was that he wasn't worried about the extra cost of actually putting the bonding in it was that we'd need to then carry out an EICR on the whole installation as we'd changed the earthing parameters of the system????

Really odd and something I'd not heard of before? Is this right? Surely it's just a matter of installing the new bonding, testing to make sure its connection and continuity is verified and is below the set parameters for resistance and then I'd carry out my continuity of CPC, Ze, Zs, PFC, PSCC and RCD tests when completing my install as I would do on all occasions no matter what anyway?

Any advice would be greatly appreciated.

Thanks in advance,

Pete.

 

[timhoward]

I'd have done what you were going to do!
I'm not sure why your boss thought that - so it's guesswork... two very wacky ideas are:
1 - he thought that by suddenly bonding the services you might be creating some extraneous conductive parts and the whole place would need a good look over to check this. I can't see this actually happening myself.
2 - He was concerned that a faulty appliance e.g. water heater, boiler would start tripping something once the services were bonded. Again, unlikely.

So I'm a little baffled too.

 

[JBW175]

Your boss is a cowboy.

Regulation 132.16 clearly states the earthing and bonding arrangements shall be adequate before carrying out additions and alterations to an installation.

 

[pc1966]

it was that we'd need to then carry out an EICR on the whole installation as we'd changed the earthing parameters of the system????

Well it might change the DB Zs value due to parallel paths, but only in the better direction.

What is important is supply earth is the Ze value, that is not changed by the additional bonding. The reason it is important is exactly this point, that if bonding is to metal service pipes that get changed to plastic then you lose the parallel paths and if Ze is not low enough to begin with you have big problems for ADS!

To me the lack of main bonding is a serious risk if it is a TN-C-S supply as under open PEN fault conditions the resulting neutral current will try to find its way home. If that is via a 0.75mm CPC to the boiler in the house a fire could start!

 

[loz2754]

The boss was right to say stop work and leave the job, as we're not allowed to make any additions or alterations unless earthing and bonding is satisfactory. And it's between him and the client as to whether to go ahead with unplanned additional works without discussing the additional cost before work commences.

I suspect he will convince the client that an EICR needs to be done in view of the lack of bonding, as there may well be other issues to be dealt with before going ahead with the planned works.

In other words he has made a financial decision based on your findings.

 

[pc1966]

The boss was right to say stop work and leave the job, as we're not allowed to make any additions or alterations unless earthing and bonding is satisfactory. And it's between him and the client as to whether to go ahead with unplanned additional works without discussing the additional cost before work commences.

I suspect he will convince the client that an EICR needs to be done in view of the lack of bonding, as there may well be other issues to be dealt with before going ahead with the planned works.

In other words he has made a financial decision based on your findings.

That is a very good point, it may be nothing to do with the electrical desirability of the bonds.

 

[Vortigern]

The boss may not (or may) always be right but the boss is always the boss.

 

[7029 dave]

Its not clear what you were there to do, but you do make a statement about carrying on with the install, so your boss should have looked/surveyed the job and would have spotted the gas and water not bonded before the said works started.

 

[cliffed]

After remedial’s either new satisfactory EICR or MWC indicating MPEC been completed & realating to EICR for a satisfactory installation