Earth wire on domestic heating oil tank - various questions

[Max Rasa]

Hi all

I had a new consumer unit fitted 3 - 4 years ago. I was never told that I had to periodically test the RCDs by pressing the T buttons. Still, you live and learn!

Anyhow, it is a split unit. The left side tripped when I hit the button. But the right side didn't. Did a bit of reading but could figure it out. Until today. I remembered that when the unit was fitted the electrician also added an earth to our domestic heating oil tank, but this had become detached. I've re-attached it and hey presto, the RCD now works when tested.

So I thought I'd better check in with you guys....

1. Does it sound right that having the earth disconnected would have stopped the RCD tripping on being tested, and re-attaching would fix it?

2. What kind of connector is it (see picture below)? When I put the earth cable into the holes, the RCD wouldn't trip. When I out it into the gap and made sure it was touching the rod, it DID work and the RCD tripped when tested. So how should the cable be connected properly to that piece?

3. Just for my curiosity, why is the oil tank earthed?

4. Do I need to somehow cover that earth point/rod so that the dogs can't get to it, people don't trip on it etc?

Here are the pics:

Cheers

Max

 

[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

 

[Midwest]

I would not Earth it with an earthrod.

You crazy guy

 

[DPG]

I would use a bonding rod. Daz

 

[westward10]

I would use a bonding rod. Daz

Would you bond the rod.

 

[DPG]

I would connect the bonding rod to an adjacent earthing rod. Belt and braces. In fact I'd earth my braces to be sure.

 

[madmaz]

I would connect the bonding rod to an adjacent earthing rod. Belt and braces. In fact I'd earth my braces to be sure.