Earth wire on domestic heating oil tank - various questions

[Barry White]

Copied and pasted a reply from the other forum contains a lot of info! Deffo same OP as same pictures etc this is from the cert.

Quote

"OK, let's see.... It's pretty much Greek to me, but I'll give you what I think might be relevant!

TN-C-S.

1-phase (2 wire)

Means of earth - Distributor's facility

Installation earth electrode - either says MA or NA.

Conductor material - copper

Condutcor CSA - 10.00mm2

Water service box = ticked

Oil service box = ticked



Do you need anything else?


Cheers"

 

[DPG]

So it looks like he's 'bonded' the oil pipe by earthing it? Daz.

 

[madmaz]

So it looks like he's 'bonded' the oil pipe by earthing it? Daz.

Sounds like it ... total lack of understanding oil pipes are generally sheathed so its highly likely he's made the installation less safe than it was

 

[DPG]

Sounds like it ... total lack of understanding oil pipes are generally sheathed so its highly likely he's made the installation less safe than it was

Sheathed or not, he's earthed rather than bond back to the MET. Total misunderstanding! Daz

 

[westward10]

Would love to know why he did it.

 

[madmaz]

Sheathed or not, he's earthed rather than bond back to the MET. Total misunderstanding! Daz

That's why I said total lack of understanding..... chances are the pipework wasn't extraeneous to start with due to sheathing and a plastic bund. that is until the sparky made it so !

 

[Marvo]

None at all, I suspect the person who did it has no idea as to the theory behind it.

Me too. The tank looks like it's plastic from the photo so the rod would only be serving the buried pipe. The way it's connected to the pipe doesn't look like it was intended as an earth point for a bulk supply truck to attach a trailing earth clamp for safety during the filling process so I'm stumped....

The missing bolt is also making me skittish. I've seen enough from the photos to second the advice of getting an experienced sparky to check it out and ramp test the RCD whilst he's there.

 

[Marvo]

If the supply to the premises is TN C S I hope it's already PME'd otherwise that pipe might get warm if there's every a DNO joint fault

 

[Barry White]

Only thing I can think of is as the oil pipe was bonded to the met inside the building and TNCS perhaps there was a touch voltage on the oil pipe at the tank between it and true earth ?

 

[Max Rasa]

Hi all

I thought I was up to date on the thread on here. Just come back and there's a page worth of posts I didn't realise were there! I guess that's the potential when you post on several forums

Anyhow, many thanks for all the posts and help. I emailed the electrician (being xmas and all) and haven't heard back. I think in the New year I'll give him a call and see what he says as to why he fitted the rod and earthed the tank. No one seems to understand why he done it. We recently had an electrician over to fit a new cooker. They had a quick look and couldn't see why he had bothered either. Not that it was entirely pointless, more just an extreme case of belt and braces!

One thought.... Our mains water comes into the house via a blue plastic pipe rather than metal. Could that be anything to do with it? Could it be that he could not earth it to the house's pipework and so had to use the rod? Please bear in mind that this is a totally uneducated stab in the dark!

Cheers for all the help.

PS - the electrician who came also ran a test on the RCD that wasn't working initially. He said it is absolutely fine.

 

[Barry White]

Thanks for updating us please update again when the electrician returns.

 

[bigspark17]

That's why I said total lack of understanding..... chances are the pipework wasn't extraeneous to start with due to sheathing and a plastic bund. that is until the sparky made it so !

So you wouldnt bond that buried oil pipe because it has a plastic covering? What happens when the plastic gets damaged or breaks down and the pipe is then extraneous?! Rediculous.. bond it!

 

[davesparks]

So you wouldnt bond that buried oil pipe because it has a plastic covering? What happens when the plastic gets damaged or breaks down and the pipe is then extraneous?! Rediculous.. bond it!

Or the joints in it which are normally exposed compression joints.

 

[DPG]

So you wouldnt bond that buried oil pipe because it has a plastic covering? What happens when the plastic gets damaged or breaks down and the pipe is then extraneous?! Rediculous.. bond it!

But he hasn't bonded it. He's earthed it with a rod. Daz.

 

[Marvo]

If it's not bonded at the other end and connected to the MET then earthing it via its own rod could cause issues in the equipotential zone of the main installation. Also, connecting it via bonding to the MET could be an issue if the installation earthing arrangement isn't PME'd by the DNO.

 

[Barry White]

More info on other forum including the cutout its TNCS and a photo of the oil pipe at the boiler it looks bonded too.

 

[bigspark17]

If the oil pipe is bonded in the house then the earth rod connected @ tank end is not creating a danger nor has it any use, classic example of somebody doing something without knowing why or what there trying to achieve.

 

[Midwest]

Perhaps they just wanted to earth the earth rod

 

[westward10]

That's funny because on TT systems I often say the conductor to the rod is doing just that, earthing the rod. Take it away it will probably make no difference.

 

[madmaz]

So you wouldnt bond that buried oil pipe because it has a plastic covering? What happens when the plastic gets damaged or breaks down and the pipe is then extraneous?! Rediculous.. bond it!

I would bond at the point of entry to the property I would not Earth it with an earthrod. My suggestion is that the addition of the earth rod has more than likely made the installation less safe