3 or 4 pole Isolator?????

[gerard]

Hi,

I am installing a new distribution board. It is supplying 2 compressors, 2 Air dryers and a 13A socket.
Is it ok to use a 3 pole isolator as a means of isolation or do I need to disconnect the neutral also?

!!

 

[davelerave]

we only have tn-c-s here so the neutral isn't switched

if you need to break all lives for TT -the isolator may edit: break neutral last and make first!


had it wrong way round

 

[gerard]

Thanks for that - so I take it I am ok to use a 3 pole isolator for the DB then?!

 

[Guest123]

For a system other than TT....yes.

 

[Rikki Barrett]

Is there any benefits to using a 4-pole device??? Is there any situation where you are not aloud to use a 4-pole device???

 

[gerard]

From what i gather you should use a 4 pole in all systems that are not TN, TN-C and TN-C-S.
I am open to correction on this!

 

[controlman]

In TNC systems the PEN conductor shall not incorparate a means of switching or isolation. In TNS the same, and PROVISION NEED NOT be made for isolation of the neutral conductor EXCEPT required for High voltage discharge lighting, water heaters and suchlike. Thats why there is a DP switch on an immersion heater.

 

[controlman]

From an inspectors point of view
3 pole - strip down the unit to get to the neutral. disconnect the neutral link (if they are fitted) reassemble the unit
4 pole - done in seconds