Earth rods...do i need one?

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Quite, although it would have taken a bit of an idiot (at least, one who didn't understand how the devices worked) to install a VOELCB if there hadn't been an earth of some sort to connect to it (even if only a service pipe) at the time, wouldn't it?
I haven't come across a working one of these yet - other than to rip out - but if the 10mm² ? earth cable coming into the CU is from a earth spike and then the 6mm² ? from the CU goes to the VOELCB does it still need a second earth cable?
 
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I always thought the point was that the installation earth goes through the VOELCB - i.e. it should be in series with the cable from the rod to the CU.
 
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I haven't come across a working one of these yet - other than to rip out - but if the 10mm² ? earth cable coming into the CU is from a earth spike and then the 6mm² ? from the CU goes to the VOELCB does it still need a second earth cable?
Yes, it certainly does - it's fault current travelling from the installation's CPCs through the coil of the VOELCB to 'true earth' that results in the device tripping. If only one end of the coil is connected, it obviously coiuld never trip.

Kind Regards, John
 
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sidecar_jon: I think the bottom line of the above is that, regardless of your answers to the questions you've been asked, you really need to get an electrician in to inspect the situation and get it sorted - because it looks and sounds pretty likely that you have an unsafe electrical installation there.

Kind Regards, John
 
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John is right. That installation needs remedial work.

Also one of the red spot fuses has been inserted the wrong way round.
 
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Yes, it certainly does - it's fault current travelling from the installation's CPCs through the coil of the VOELCB to 'true earth' that results in the device tripping. If only one end of the coil is connected, it obviously coiuld never trip.
I should perhaps have added that this is the reason why 'voltage-operated' (as in VOELCB or ELCB-v) really is/was pretty misleading. It is fault current flowing through the device's coil that results in its operation - which sounds pretty much like 'current-operated' to me! They got their name because the impedance of the coil (IIRC in the range 150-500Ω) was such that the current required to trip it arose when the voltage across the coil (i.e. the voltage between CPCs and true earth) rose to a particular 'safe' level (I think nominally 50V, but often about 35V in practice). The device would hence operate if a 'dangerous' voltage (>50V) arose between CPCs and earth, but it was the current resulting from that voltage which actually caused the device to trip.

Kind Regards, John
 
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Ok the green/yellow cable at the top was put in by the central heating guys and it runs over the door and to the copper gas pipe in the meter cupboard on the floor on the opposite side of the porch.

you guys throw acronym round like cows in a hurricane!..is there some web site or explanation of all this in a simple format that an electrical idiot might have a chance to understand?

So whats the water/gas pipe thing for? should i have them?


Oh yes the yellow button trips everything out much to the disgust of my F12013 playing son.
 
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Ok the green/yellow cable at the top was put in by the central heating guys and it runs over the door and to the copper gas pipe in the meter cupboard on the floor on the opposite side of the porch. you guys throw acronym round like cows in a hurricane!..is there some web site or explanation of all this in a simple format that an electrical idiot might have a chance to understand? So whats the water/gas pipe thing for? should i have them?
OK. Sorry about the acronyms in the discussions we've been having. As I said, the bottom line is that you need an electrician to look at all this.

Green/yellow cables connecting your electrical installation to incoming gas (and water) pipes are required - that one to the gas is probably OK, but it's not clear whether there is also one to the water pipe.

However, gas and water pipes have not been acceptable or allowed, as the only means of earthing for decades. You also need an 'earth rod' (like your neighbours).

That black thing with a test button is one of the 'voltage-operated ELCBs' we've been talking about here. It was an early attempt at a safety measure, but is now obsolete, not acceptable and needs to be replaced with a modern Residual Current Device ('RCD') - both to comply with regulations and for your own (and your house's) safety. As I've said, the existing one does not even look as if it has been wired correctly (one earth connection missing), so probably would not work at all (even if the test button makes it trip).

There may be other things wrong, but you really do need an electrician to get it sorted out.

Kind Regards, John
 
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ok thanks for that..would a new "whole box thingy" ie the fuse thing replaced by a new box thing with circuit breakers sort all that out?

I don't think its all grounded to the water pipes, partly because the water pipes come up through the neighbors walk way (ope way) go up to the bathroom (that's actually over the neighbors property!) but to get to the kitchen at the back comes off a different pipe that i suspect isn't even on the same stockcock..And there are no wires going to any pipes i can find.

Part of my original question remains though, Ive seen wire's from water pipes which seem to go to ground, what are they for? Can it be to ground static electricity? Though i'd think the pipes did that anyway!.
 
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You also need an 'earth rod' (like your neighbours).
Well...

ms5k.jpg


Before going down the TT route it would be worth asking the DNO if a PME supply is available.
 
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ok thanks for that..would a new "whole box thingy" ie the fuse thing replaced by a new box thing with circuit breakers sort all that out?
Not completely. It might sort out the 'RCD' business, but there would still be the problem that you don't currently appear to have a proper earth.
I don't think its all grounded to the water pipes, partly because ......And there are no wires going to any pipes i can find. Part of my original question remains though, Ive seen wire's from water pipes which seem to go to ground, what are they for? Can it be to ground static electricity? Though i'd think the pipes did that anyway!.
There is a requirement that the 'earths' of your electrical installation are connected to any water or gas etc. pipe which enters the property, to make sure that, under certain fault conditions, is is not possible for dangerous voltage differences to arise between electrical things (e.g. kettles) and pipes which might be touched simultaneously. Electricians call that 'bonding'.

However, you also need a proper earth - either from your own earth rod or an earth provided by your electrical supplier. As BAS has just pointed out, it looks as if your supplier might be able to provide such an earth (so you wouldn't need an earth rod) - so I would suggest that you ask your electrician to look into that possibility.

Kind Regards, John
 
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Before going down the TT route it would be worth asking the DNO if a PME supply is available.
Well spotted. It clearly once was (or was meant to be) a TT installation - but, as you point out, it may not have to stay that way.

Kind Regards, John
 
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There is an urgent need to get a competent electrician.

There is a requirement that the 'earths' of your electrical installation are connected to any water or gas etc. pipe which enters the property,
When the CPC ( the "earth" wire ) is not connected to an effective earth in the event of a Live to CPC fault the CPC potential will rise up to live potential. Not a hazard within the equipotential zone inside the house. But if the gas or water pipe are metallic through to the outside of the house the external metal sections will, via the bond to the CPC, become live potential and thus hazardous to anyone touching them.


Also as there is no effective earth leakage detection and disconnection unit ( RCD or VOELCB ) and apparently no low impedance grounding of the CPC a Live to CPC fault would not not operate any disconnection device.
 
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There is an urgent need to get a competent electrician.
Indeed. We said that quite a while back and it remains true. I realise that the installation may have been in it's present state for years, or decades, but once one becomes aware of the problem, it really should be sorted out pretty quickly - since there is no telling what might happen 'tomorow'.

Kind Regards, John
 

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