Sky high ze reading

[Sparksaflyin]

Hello fellas. Had the dno trying to tell me that a 19 ohm ze reading on a tns system was ok to leave energised? Seriously? Can someone please explain to me how that is ok?

 

[ferg]

On an EICR that would be a C2.

I guess they are applying the same rules as us, C2 requires urgent remedial action but you would not normally be expected to disconnect the installation because of it.

That is of course on the basis that they plan to do something about it.

 

[buzzlightyear]

Hello fellas. Had the dno trying to tell me that a 19 ohm ze reading on a tns system was ok to leave energised? Seriously? Can someone please explain to me how that is ok

TN-CS (PME) 0.35ohms TNS - 0.8ohms did they come round to test it or was it over the phone you told them .so a higher ZE may not be an issue if the dno decide that its down to network parameters. All they would do is ensure the main fuse is sized appropriately.

 

[Strima]

Did you speak to anyone of importance on the phone or just the trained chimp who answered the phone?

 

[davesparks]

Hello fellas. Had the dno trying to tell me that a 19 ohm ze reading on a tns system was ok to leave energised? Seriously? Can someone please explain to me how that is ok?

only the person who told you it is ok can tell you why they said that, we cant read their minds any more than you can.

Exactly what did they say about it? did they say it is ok for now until we can get it fixed or that it is ok permanently? did they confirm whether the installation had suiatble RCD protection to make this ok as a short term soloution?

 

[Sparksaflyin]

Hello again. It wasn’t me who spoke to them on the phone so I have no idea if they were important. I installed a new fuseboard and when it came to testing the ze i obviously came across the reading. They sent someone out and that was when he told me the reading is fine providing it has suitable rcd protection, which it has. It’s a full rcbo board and the operating times were well within boundaries. I didn’t argue with him as I don’t deal with their side of things and therefore wouldn’t question that I know more about his job than him but personally I would not have been happy to walk away and leave it. They are supposed to be going back tomorrow morning to fix the issue though

 

[7029 dave]

Is the DNO taken ownership of this Earthing arrangement.? If so its their baby.

 

[Sparksaflyin]

Yes they are going to sort it tomorrow. I was just curious how this could be deemed safe.

 

[Baddegg]

I always test Ze before changing the unit....never had any readings like yours @Sparksaflyin, but always done it that way...if the dnos been out and physically checked it’s on them now

 

[Strima]

So they haven’t ignored it then? As it has suitable RCD protection then they deemed it safe for continued use until they can rectify the poor earthing fault.

 

[davesparks]

Hello again. It wasn’t me who spoke to them on the phone so I have no idea if they were important. I installed a new fuseboard and when it came to testing the ze i obviously came across the reading. They sent someone out and that was when he told me the reading is fine providing it has suitable rcd protection, which it has. It’s a full rcbo board and the operating times were well within boundaries. I didn’t argue with him as I don’t deal with their side of things and therefore wouldn’t question that I know more about his job than him but personally I would not have been happy to walk away and leave it. They are supposed to be going back tomorrow morning to fix the issue though

So they are saying it is OK for 24 hours just until they fix it tomorrow, which makes perfect sense. That's very different to saying it is good for continued service as your first post suggested.

There is no need for anyone to argue with him, that kind of confrontational attitude will only lead to trouble, a sensible and well reasoned technical discussion would be a far better idea.

As others have said if this was an issue in the installation then it woukd be a C2 on an EICR and is not immediately dangerous, only potentially dangerous. The presence of RCD protection for all circuits reduces the danger to an acceptable level for the short term.

 

[Sparksaflyin]

Thanks for the input Dave. My post may have suggested that but I never actually said it was going to be left like it permenently and also I actually made a point of saying in my post that I didn’t argue with him. Why would I? As I said in my post he will know his job better than I do. I just assumed from the conversation my colleague had on the phone to the dno that as it was a potentially a very dangerous sotustion, that they would atleast put some effort in to stay and correct the fault there and then

 

[richy3333]

I had an issue with Hydro where the external loop impedance was 1.1 ohms on a TNS system. They said they would take no action until it went above 1.5 ohms.

 

[snowhead]

but personally I would not have been happy to walk away and leave it.

So was the installation left isolated by yourselves pending arrival of the D.N.O?

 

[Sparksaflyin]

So was the installation left isolated by yourselves pending arrival of the D.N.O?

I waited there until they arrived

 

[Sparksaflyin]

So...
You didn't bother to get yersen a Ze first... before doing your stuff...?

See how now your responsible for getting it sorted for em...?

I’m only responsible for getting the dno out to sort their problem. Once it’s handed over to them it’s out of my hands. That’s how I see it anyway

 

[davesparks]

I’m only responsible for getting the dno out to sort their problem. Once it’s handed over to them it’s out of my hands. That’s how I see it anyway

But you have to go back again once it has been fixed to do the live testing don't you?

 

[7029 dave]

Here we go.!!!!

 

[DPG]

Just like old times.

 

[Des 56]

Before the universal reliance on Rcds,if the same situation arose on a system in the past ,that high reading may have led to getting advice to provide Rcd protection until its sorted,same as now

Perhaps its the workplace perception of the potential danger that is changing as the system protections gets better