Advice on regulation 521.5.1

[Risteard]

exactly what i was getting at, the earth is only live during fault conditions

That isn't true. There will be a certain amount of legitimate earth leakage from appliances. Don't forget that there is functional earthing as well as protective earthing.

And as pointed out, under fault conditions there could be a significant current flowing.

 

[Deleted member 26818]

Also there will be some voltage and current on the earth conductor where PME conditions apply.

 

[R G]

So are the wylex tail glands with the 2 holes only not be used then?

Wiska make glands that have 3 holes in and made for this purpose ..

 

[Dave OCD]

Hate as in I have a phobia of them. I cannot stand to be in close proximity to small children and babies.

That's an unusual one, I have the same problem with snakes.:smile5:

 

[Lucien Nunes]

When the SWA is used as the CPC outside the box, and a length of 6491X lugged onto the banjo bolt serves on the inside, the low resistance path connecting them together is via the brass of the banjo and the bolt, rather than through the enamelled steel enclosure which might make relatively poor contact and is of lower conductivity compared to the brass. So in the event of a fault the banjo bolt carries most of the fault current through a separate hole.

What's the solution? Single hole banjo? Moebius bolt that goes through both holes and back to where it came from? Slot the banjo bolt hole across to the gland entry?

 

[R G]

That's an unusual one, I have the same problem with snakes.:smile5:

Funny that I have the same , must stay off this forum ...

 

[netblindpaul]

When the SWA is used as the CPC outside the box, and a length of 6491X lugged onto the banjo bolt serves on the inside, the low resistance path connecting them together is via the brass of the banjo and the bolt, rather than through the enamelled steel enclosure which might make relatively poor contact and is of lower conductivity compared to the brass. So in the event of a fault the banjo bolt carries most of the fault current through a separate hole.

What's the solution? Single hole banjo? Moebius bolt that goes through both holes and back to where it came from? Slot the banjo bolt hole across to the gland entry?

Do like I do and put the banjo inside?
Not an issue really outside or inside, the contact area is greater inside, than out.
Don't drill the enclosure, why would you?

 

[Dave OCD]

That isn't true. There will be a certain amount of legitimate earth leakage from appliances. Don't forget that there is functional earthing as well as protective earthing.

And as pointed out, under fault conditions there could be a significant current flowing.

There is no functional earthing in a domestic installation.

 

[Risteard]

There is no functional earthing in a domestic installation.

There mightn't be much, but I wouldn't say none (on appliances).

 

[Lucien Nunes]

Indeed, functional earthing is where most legitimate leakage current comes from. Not that it has anything much to do with eddy currents - they start being a problem with hundreds of amps, not a few mA.

 

[Risteard]

Indeed, functional earthing is where most legitimate leakage current comes from. Not that it has anything much to do with eddy currents - they start being a problem with hundreds of amps, not a few mA.

Completely agree. Just pointing out that it isn't correct to state that there can be no current on the Earthing Conductor without a fault current.

 

[Dave OCD]

There mightn't be much, but I wouldn't say none (on appliances).

I was thinking along the lines of the installation rather than connected appliances.:smiley2:

 

[shanky887614]

Indeed, functional earthing is where most legitimate leakage current comes from. Not that it has anything much to do with eddy currents - they start being a problem with hundreds of amps, not a few mA.

thats my point, you wouldn't get 100amps flowing on the earth in a domestic property

in commercial/industrial yes it is something to consider because of the size of the supply etc.

now i will follow the reg but im just saying in my opinion its belt and braces with reguards to the earth

if people have safely put the earth in the board for the last 100+ years i doubt it is cause for concern

 

[Dave OCD]

Maybe momentarily under extreme fault conditions but unlikely.

 

[shanky887614]

Maybe momentarily under extreme fault conditions but unlikely.

a fault current that high would melt the copper where the fault is located and clear it before the eddy currents would start to work on the earth

i doubt 6ka fault current would be enough to instantly cause noticble affects on the install before it trips the breaker

 

[Dan]

Just bumping some threads in the Electrical Wiring Theories and Regulations forum category here on our Electricians Forums. If this specific topic isn't current, just ignore it, it'll drop off the list in no time. However, if it's something you'd like to contribute to, feel free to reply and bring it back into current discussion.

 

[HappyHippyDad]

You chose to bump this thread Dan!!!
Could get interesting if the same characters are still around