Help! Trying to confirm if earth wire is connected

paolouno

Hi all,

I'm installing a couple of lights in the garden (the push-in metal spike type) and will be connecting them to a 4-core armored cable already left there for the purpose. I've identified the live and neutral, but the lights also require an earth connection. I believe (!) that one of the remaining cores is being used as the earth, but can't physically check because the armoured cable connection joint is now underground.

So my question is: how can I make sure that the core I think is an earth actually is, rather than just being unconnected at the other end? I have a multimeter, but no fancy gear...

Thanks!

hufpc8w3adnk65

paolouno wrote: »

Hi all,

I'm installing a couple of lights in the garden (the push-in metal spike type) and will be connecting them to a 4-core armored cable already left there for the purpose. I've identified the live and neutral, but the lights also require an earth connection. I believe (!) that one of the remaining cores is being used as the earth, but can't physically check because the armoured cable connection joint is now underground.

So my question is: how can I make sure that the core I think is an earth actually is, rather than just being unconnected at the other end? I have a multimeter, but no fancy gear...

Thanks!

Call an electrician!

BrianDug

Edit: As MrMac84 said your best bet is to call an electrician, you dont want to mix up the neutral & earths as it will be dangerous.

hufpc8w3adnk65

The fact the OP is surprised at outside lights NEEDING an earth shows he should be no where electricity!

paolouno

My orignal post might have been a bit unclear, so let me try again. The cable has 4 cores (brown, blue, black grey). The brown and blue are, unsurprisingly, live and neutral respectively. One of the others is being used for the earth, and one is spare. How can I be certain which is of these two remaining cores is the earth (and check that it is properly connected) and which is unused, ie not connected to anything at the far end.

Thanks

2011

To establish this it would be best to:

1) Ensure that the earthbar in the main distribution board is not neutralised (during the test only). It would be best to have the entire board powered down for this.

2) Use a multimeter and "wander lead" to establish which (if any) core is connected to earth.

As the other posters have said this is work best carried out by an electrician. It would be advisable to ensure that these lights are protected by an RCD or better still a dedicated RCBO.

When complete the new part of the installation should be tested (insulation resistance, earth fault loop impedance etc...) and certified (ideally).

Steve

2011 wrote: »

and certified (ideally).

AFAIK, it can't be certified if an incorrectly coloured earth wire is used (i.e. something other than GN/YE).

I'm actually surprised that a cable exists that is rated for mains voltage and has current three phase colour codes yet doesn't contain a PE conductor.
Is it still permitted to use the SWA as the PE (thought that was abolished, I'm not current on much outside of factory automation these days)?

Bruthal

Steve wrote: »

I'm actually surprised that a cable exists that is rated for mains voltage and has current three phase colour codes yet doesn't contain a PE conductor

You wouldnt see too many 5 core SWA cables being run in here anyway. 4 core and separate earth usually.

crazy_kenny

Remove cover of circuit board. See what core is connected to earth bar.

In Ireland the neutralization of the earth bar occurs in ESB connection box.

2011

Steve wrote: »

AFAIK, it can't be certified if an incorrectly coloured earth wire is used

I have seen many certified installations where cables are sleeved green/yellow. Personally I can't see the issue when done properly.

I'm actually surprised that a cable exists that is rated for mains voltage and has current three phase colour codes yet doesn't contain a PE conductor.

It is readily available. In fact 3 phase motors fed from VSDs that are wired in SWA should be 3 core and must not contain a CPC, this should be run separately (EMC regulations AFAIK). Failure to do so can cause issues with harmonics.

Three core SWA/XLPE/LSF cables are very common in industrial installations.

Is it still permitted to use the SWA as the PE (thought that was abolished, I'm not current on much outside of factory automation these days)?

Yes, once it can be demonstrated that the disconnection times can be met. However it is not normal to do this.

Steve

2011 wrote: »

I have seen many certified installations where cables are sleeved green/yellow. Personally I can't see the issue when done properly.

Sound, as I said I'm not current on what passes in domestic situations. Last I heard of it was IEC rules stated PE conductors were to be continuously identified throughtout their length - that was back in the panel builder days and was about 15 years ago.

It is readily available. In fact 3 phase motors fed from VSDs that are wired in SWA should be 3 core and must not contain a CPC, this should be run separately (EMC regulations AFAIK). Failure to do so can cause issues with harmonics.

What reg is that? EMC Directive does not specify anything there..

2011

Steve wrote: »

Sound, as I said I'm not current on what passes in domestic situations.

I have not worked in domestic installations myself for many years.

Last I heard of it was IEC rules stated PE conductors were to be continuously identified throughtout their length

You may well be correct, it may be a regulation that is simply ignored.

EMC Directive does not specify anything there..

Really? I had an ABB engineer on commissioning VSDs on a project last year. My recollection was that he stated this, I am a bit foggy on the EMC directive to be honest hence the "AFAIK" part in my post.

Steve

2011 wrote: »

Really? I had an ABB engineer on commissioning VSDs on a project last year. My recollection was that he stated this, I am a bit foggy on the EMC directive to be honest hence the "AFAIK" part in my post.

I really don't want to go off topic here but I've had conflicting views from various reps of reputable suppliers about their views on EMC stuff, I take most with a grain of salt as the solution ultimately means buying more stuff from them. Another thread perhaps..

paolouno

Thanks for the info guys. Regarding identifying the earth using multimeter - is that just a continuity check with the earth loop in the domestic wiring, or is there some cleverer way?

2011

paolouno wrote: »

Thanks for the info guys. Regarding identifying the earth using multimeter - is that just a continuity check with the earth loop in the domestic wiring, or is there some cleverer way?

Pretty much, yes. However most installations in Ireland are neutralized. Therefore a core that appears to be an earth may be a neutral! Using a neutral as an earth in this scenario would not be advisable. For this reason I would ensure that the neutralizing link is out of circuit. I would resolve this at the distribution board, not at the ESB meter.

It is important to note that without proper testing it is not possible to ascertain that the earth is fit for purpose or that the rest of the circuit is.

In general it is easy to get anything electrical working, the trick is to get it working safely (as per ETCI regulations), correctly (as the manufacturer intended) and within budget.

Nobody cares about safety until something goes wrong!

intbn

2011 wrote: »

In general it is easy to get anything electrical working, the trick is to get it working safely (as per ETCI regulations), correctly (as the manufacturer intended) and within budget.

Nobody cares about safety until something goes wrong!

Couldn't of put it better meself 2011!