What is this?

[VoltzElectrical]

I was chatting to my neighbour over a cup of tea today when he mentioned his wide had bought some fancy metal switches for the kitchen. He then went on to explain that when he took the faceplate off he found this, then promptly put it back on again!

I had a look, and it's weird. Does anyone know just what the hell that is in the back box? It doesn't look or feel like rust, more like hardened resin residue of some sorts.

Anyway, after a bit of a look around, I asked to look at the fuseboard because I wanted to know how to isolate the switch to replace the box. Located outside in a gas box! new meter, TN-S system but check out the size of the earth! looks like 2.5mm. I recommended he upgrade the main earth, and got a Ze reading of 1.16 ohms. Thought I'd check Zs at the switch, 2.72 ohms.

No bonding. Discussed this with him, gas is a right pain to get too, BEHIND kitchen units, water under sink.

Can you run bonding cables outside then make connections inside?

How would you upgrade consumer unit given the space?

I'd be tempted to do the bonding, upgrade the main earth and leave it the hell alone. After all it's worked for years. Failing that it's relocate the whole lot on the other side of the wall on the inside of the property with longer tails as I'lll never get a new board in that space.

Anyway, all thoughts welcome. The original question is What is THAT in the back box? Weird that.

Oh, and all I'm planning is isolating the switch, replacing the back box, lose the supply to the outside light (not needed) and tape up the nicked cable. For another cup of tea!

Cheers.

 

[telectrix]

Yuk.....

 

[leesturgess]

double yuk

 

[VoltzElectrical]

Yuk.....

come on Tel, i need TECHNICAL terms! Have you EVER seen ANYTHING like this? Is it ectoplasm, hardened?

 

[MarkieSparkie]

Hi Voltz,
Running your main bonding cables outside and terminating them inside is obviously not ideal, but there is nothing wrong in principle with doing so.
I think you will need to hack that gunk - seen similar, in that case it was burnt and heat exposed expanding foam caused by a in-line crimp terminal which had not been crimped - out of the back-box, if only to access if there is any damage/deterioration of the conductor insulation and the connector blocks.

 

[VoltzElectrical]

Zs ok at switch? think 7.7 ohms maximum for 3036 on 0.4 disconnection time on TN-S. I s that correct? With these ZS times is there any point in upgrading the main earth?

 

[VoltzElectrical]

Hi Voltz,
Running your main bonding cables outside and terminating them inside is obviously not ideal, but there is nothing wrong in principle with doing so.
I think you will need to hack that gunk - seen similar, in that case it was burnt and heat exposed expanding foam caused by a in-line crimp terminal which had not been crimped - out of the back-box, if only to access if there is any damage/deterioration of the conductor insulation and the connector blocks.

Cheers Markie. No sight of expanding foam. Plan is to isolate, replace back box then it's up to him wether he still wants the flat plate chrome switches. There is some slight cable damage to the main live conductor that needs taping up. I will basically try to tidy up a 'yuk'.

And he doesn't seem too fussed on the bonding. If accessibility to too hard, can you bond gas outside of the recommended 600mm or whatever it is? Will try to convince him. Any thoughts on upgrading the main earth with those Zs values. or should i just do it anyway seeing as its a 400mm run?

 

[Richard Burns]

Looks like some sort of secreted resin.
Yeah, but secreted from what?

 

[VoltzElectrical]

Aliens?

 

[Richard Burns]

Sorry about that, couldn't resist.
Actually looks like the sort of mess you get when there is some acid about as well (or possibly alkali from plaster), the iron gets wet with acid and rusts and forms compounds with the acid, this then dries out to the mess you have.
The bonding within 600mm is where practicable (not an excuse for laziness) that does give some leeway and I think GN8 says something about bonding outside in the gas meter box. (i haven't received GN8 yet waiting for the new one). I think it would be a good idea to upgrade the earth CCC is bit low in fault conditions.

 

[topquark]

Aliens?

Wasn't me!

 

[Knobhead]

come on Tel, i need TECHNICAL terms! Have you EVER seen ANYTHING like this? Is it ectoplasm, hardened?

Yes, but not even my ex wife would put wire in a mince pie. She knew I wouldn’t eat anything sweet!

It looks like calcium hydroxide reacting with copper to form copper carbonate, but heat is needed to do that. A bad connection and damp leaching out of cement could cause it. Once you start to form carbonates they grow in physical size, they are also conductive unlike many oxides.

Other than that it’s all down to the mince pies!

 

[GLENNSPARK]

Zs ok at switch? think 7.7 ohms maximum for 3036 on 0.4 disconnection time on TN-S. I s that correct? With these ZS times is there any point in upgrading the main earth?

But this may be due to parrallel paths mate......you need to get that Ze down to within 0.8 mate..........

 

[GLENNSPARK]

And dont forget to do the x0.8 correction for tabulated values of Zs for ambiant tempreture.........

 

[GLENNSPARK]

sorry guys...just done the calc and its 7.66.....for 5A