Switched Neutrals or not

[Overtaker]

This question is purely out of interest, I'm a substation apprentice while we do some LV installation work its not much and no design work fitting only.

But today I've been helping a sparkie friend do some work(just attaching conduit to wall no actually wiring) for local community group.

So the question why is the neutral to the DB from a switched fuse isolated (if that the right term) not switched but at the DB it's self does switch neutrals?
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[Dennis Alwon]

What is a db?

 

[Tony S]

Typical, I’ve just answered a question asked by an American on an English site now it’s the other way around.

Do you have a copy of BS7671? You need to work to it for anything other than DNO distribution systems.

A method of disconnecting the neutral is only required at the first DB (Distribution Board). It could be a switch with a late break, early make neutral or a bolted link. Disconnecting the neutral isn’t normally required except for testing. There is an exception for TT systems where RCD’s or RCBO’s should break the neutral, personally to my mind it should apply to all systems.

If you’ve been working on substation LV systems this should have been explained to you. For this type of work BS7671 doesn’t apply, you should be working to whatever DNO’s COP.

DNO = District Network Operator
COP = Code Of Practice

 

[Besoeker]

This question is purely out of interest, I'm a substation apprentice while we do some LV installation work its not much and no design work fitting only.

But today I've been helping a sparkie friend do some work(just attaching conduit to wall no actually wiring) for local community group.

So the question why is the neutral to the DB from a switched fuse isolated (if that the right term) not switched but at the DB it's self does switch neutrals?
​

Is this a UK installation? If so, you might do better at:
https://www.electriciansforums.co.uk

 

[Adamjamma]

But I too question why the neutral should be broken by the switch. I know that if one switches the neutral, then according to the BS7671 it should be after or simultaneous to the live but unless one is using a double pole switch, such as we use for above counter switching for under counter appliances, like the 45 amp stove switch...
why would we want the neutral to be switched off when we want it for possible faults?

 

[Besoeker]

What is a db?

Usually Distribution Board in this context.

 

[Tony S]

Back to switched neutrals. These switches (EE CFS) had a neutral link that could be opened for testing, the switch couldn’t be closed unless the neutral was in place.

BTW, it is my fat stomach



I was there to assess the distribution system, condemn more like.