IET logo
 
IET
Decrease font size
Increase font size
Topic Title: when to use 3 pole or 4 pole main switch
Topic Summary:
Created On: 21 March 2013 06:49 PM
Status: Read Only
Linear : Threading : Single : Branch
<< 1 2 Previous Last unread
Search Topic Search Topic
Topic Tools Topic Tools
View similar topics View similar topics
View topic in raw text format. Print this topic.
 16 November 2013 09:42 PM
User is offline View Users Profile Print this message



leckie

Posts: 4320
Joined: 21 November 2008

So, are we now agreeing that a 4 pole isolator is only required for a TT system?
 16 November 2013 10:53 PM
User is offline View Users Profile Print this message



jcm256

Posts: 2300
Joined: 01 April 2006

With two supplies Mains or Generator, in some cases you need to fit a 4 pole change-over-isolator (or contactor) if your mains supply is TN-S, otherwise your DNO or IDNO mains supply would be changed to TN-C-S via the earth/neutral link at the generator terminal box when supplied from a three phase generator, (Island mode operation). Some of that may be superfluous there are variations, like one supplier "only" supplied by the DNO or IDNO transformer where the neutral/earth is linked at the transformer anyhow, and then a solid un- switched neutral change-over-isolator may be ok with their permission. It is interesting the comments about four pole devices deployed with UPS and generator systems. how long have you got if you use a 4 pole COS, between mains off and generator can be seamless to an extent but electronics is even faster than a micro mill second when you loose that neutral. Just being bold in expressing ones view, badly written but what could you have me retract, no need it all works somehow.
Regards
jcm
 24 June 2015 09:11 PM
User is offline View Users Profile Print this message



leegibbins

Posts: 2
Joined: 11 May 2013

Anyone ever considered the use of overlapping neutrals?
IET » Wiring and the regulations » when to use 3 pole or 4 pole main switch

<< 1 2 Previous Last unread
Topic Tools Topic Tools
Statistics

New here?


See Also:



FuseTalk Standard Edition v3.2 - © 1999-2017 FuseTalk Inc. All rights reserved.

..