Mains switches

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JamieP
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Mains switches

Post by JamieP »

Quite interesting that I've just had a look through but the term main switch only seem to have been a thing once 3000 arrived

I can't find much in past Regulations but just curious if the term main switch was used in the industry prior to this or if people referred to the incoming isolation switch as something else
AlecK
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Re: Mains switches

Post by AlecK »

I've never heard of a main switch being called anything else but 'main switch'; except where there is more than one level of control.
Eg where lighting & power were separately metered; there would be a "main switch' for each, and a "master switch" upstream of them

They have been "main switch(es)" all my working life ( and long before).
1976 Regs used the term [R 35] (Fig 1 & Notes - but not in the Reg itself)
1993 Regs was when we began the move to Regs setting high-level outcomes with detailed riles in codes of Practice and/ or Standards.
This may explain why the term seems not to have been used in 1993 or 1997 Regs.

Noting that there's no definition for 'main switch' in Act or ESRs - which will be because the term isn't used in these documents.
In Wiring rules, no particular definition in clause 1.4; but effectively defined in 2.3.3
by their function of being isolating devices for use in emergency while maintaining supply to safety services.
Mostly they are required to be at 'main switchboard'.

There are plenty of switches labelled as 'main switch' that don't fit the location aspect of this definition - being in DBs.
But of course some of these would have been installed before the current de-facto definition came into use.
JamieP
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Re: Mains switches

Post by JamieP »

Oh yeah, I see the term Main Switchgear now

Interesting

It just got me thinking in regards to how today's rules can be applied to existing installation in regards to different terms used for things over the years, mainly in regards to people discussing things such as "main switch" heights on old switchboards in regards to switchboard upgrades and the maintaining/replacement vs installation/low risk vs high risk arguments. Obviously we clearly know what a main switch is in regards to todays rules but I just wondered if past Regulations actually called such a switch a main switch or despite doing the same thing, if it technically was a main switch back then or if it had some other name or identification

I can see in past Regulations there isn't any height requirements for such a switch but main switchboards seem to have to needed to be "Readily Accessable" and there is a definition of this in the 1976 Regs that seems similar to todays. Guess depends if you think the switchboard meets this still if it can remain in service under ESR113 and be replaced/maintained as is. With a lot of them being quite high and above doors etc doesn't really seem to meet readily accessable as per that definition.
AlecK
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Re: Mains switches

Post by AlecK »

Given that up to 1993 ALL installation work was subject to inspection; I believe we can safely assume that the location & accessibilty of switchboards was accepted by the (then ) Electrical Supply Authority as being compliant with requirements of the time.
Of course the building structure may have changed; leading to possibility that it no longer complies for purposes of ESR 113.

A swbd being above a door doesn't necessarily take it out of "readily accessible".
A main switch sitting above a 6 foot / 1800 mm door can be operated - by an adult - without climbing.
Compare "arm's reach" which goes up to 2.5 m.

As for installation vs maintenance; replacement of a single fitting is clearly maintenance.
Replacing several fittings at same time is still maintenance.
Including replacing all the fittings that make up the assembly called a 'switchboard".
The twist in that case being the follow-on requirement in 2.6.3.4 to add RCD protection; which can't be replacement.

If course it would generally be preferable to relocate the swbd as well as replace it; but that would be making an alteration.
It would also tend to add significant cost.
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