Low insulation resistance reading

[nicebutdim]

I want to create a new code for that:
PI : Potentially Interesting

Pretty certain I only ever see 3 pole main switches with removable neutral link. Maybe OP or @Risteard can confirm or make me look foolish

 

[mainline]

Pretty certain I only ever see 3 pole main switches with removable neutral link. Maybe OP or @Risteard can confirm or make me look foolish

You need a special switch if you want to switch 3 P and N - one where the neutral contact is set back so it closes early and breaks late, relative to the 3 phases.

 

[nicebutdim]

You need a special switch if you want to switch 3 P and N - one where the neutral contact is set back so it closes early and breaks late, relative to the 3 phases.

4 pole main switches are fairly common here, but the point was more about the fact we're free to use them, whereas I believe they can not be used in IE.

 

[mainline]

4 pole main switches are fairly common here, but the point was more about the fact we're free to use them, whereas I believe they can not be used in IE.

What about if its TT earthing ?

 

[nicebutdim]

What about if its TT earthing ?

I guess that might be different and something I hadn't considered.

 

[Risteard]

What about if its TT earthing ?

TT (Direct) Earthing is essentially non-existant within the State, bar perhaps a very few relics. TN-C-S (Neutralised) applies to very nearly 100% of electrical installations.

 

[MDJ]

I could be wrong, but have a funny feeling that regulations in IE require that 3 pole isolation is used and neutral shouldn't be broken. Perhaps this only applies to the main isolator or perhaps it doesn't apply at all...

should never break a neutral via a switch , if it hangs you can end up with 400 volts on a 230 volt circuit which will cause havoc.

 

[mainline]

should never break a neutral via a switch , if it hangs you can end up with 400 volts on a 230 volt circuit which will cause havoc.

On a TT you need to isolate all conductors including the neutral, hence the switch where the neutral contact is set back so it closes early and breaks late, relative to the 3 phases.

 

[nicebutdim]

should never break a neutral via a switch , if it hangs you can end up with 400 volts on a 230 volt circuit which will cause havoc.

I'd agree where functional switching is concerned, but isolators are manufactured for a specific purpose and to specific standards - there should be no danger of any live conductor 'hanging'.

 

[mainline]

TT (Direct) Earthing is essentially non-existant within the State, bar perhaps a very few relics. TN-C-S (Neutralised) applies to very nearly 100% of electrical installations.

No caravan parks, swimming pools, stables etc ? That would use TT earthing ?.