While I am asking basic question - here is 1 more

[Inteificio]

What protection does a CU main switch offer?

Is it just a switch or does it offer overload protection too?


I have asked a few sparks, and every one said it offers overload.
When pressed for what would cause it to disconnect they did not know.

So anyone know anything about this?

 

[Plonker 3]

No it is exactly as it says a switch, the current rating is just the maximum current it allows to flow through it before it would start to overheat and get damaged.

 

[telectrix]

you have been told wrong. a main switch offers no protection whatever. it's just a 2 pole isolator. the rating ( 80A, 100A, whatever) is just the maximum operating current of the switch. ( unless, of course, it's a RCD main switch, which was common some years ago.)

 

[Inteificio]

So The RCD ones are just a switch with an RCD too?

Would keep it nice and simple.

 

[Jay Sparks]

What protection does a CU main switch offer?

Is it just a switch or does it offer overload protection too?


I have asked a few sparks, and every one said it offers overload.
When pressed for what would cause it to disconnect they did not know.

So anyone know anything about this?

:nono:


As the lads above have said, its just a switch.

 

[Plonker 3]

Just be careful as this question was asked a few months ago and a couple of members got a ban for having a go at the OP for not knowing this.

 

[telectrix]

basically, a standard RCD which is also used as a main switch. this was common under the earlier 16th ed. boards, before split boards and dual RCD boards became prevalent.

 

[Guest55]

Just be careful as this question was asked a few months ago and a couple of members got a ban for having a go at the OP for not knowing this.

that would be me lol.
my first week on the forum too.
a day to cherish

In fairness , to not know this was pretty poor.

 

[telectrix]

in the last week or so there have been several posts where posters have thought that the rating on a main switch was it's trip current. the OP is not alone .

 

[Jay Sparks]

Just be careful as this question was asked a few months ago and a couple of members got a ban for having a go at the OP for not knowing this.

It wasnt aimed at the OP. It was aimed at the sparks he asked. I couldnt find a smiley face that was shacking his head.
No mallace was intended.

 

[telectrix]

It wasnt aimed at the OP. It was aimed at the sparks he asked. I couldnt find a smiley face that was shacking his head.
No mallace was intended.[/QUOTE

yes, i know what you meant. my post was also aimed at anyone who might try shooting the OP down.

 

[ackbarthestar]

Its always a good idea to refer back to BS7671 and look at table 53.2

There you have

Isolators
CBs and MCBs
RCCBs and RCDs
Functional switches

That might be why BS/EN/ISO numbers are required on all certification.

 

[Inteificio]

Thanks,

I was working a couple of months back and realized it was something I did not know that I really really should.

I asked the guy I was apprenticed too, Mr 2391, experience is everything and he said it had overload.
As on principle I do not trust a word he says thought it would be an idea to double check, it took me this long to remember when I was next to a PC.

This guy is head of an electrical engineering department, he couldn't even do a cable calc and thought that it was dangerous to check voltage between phases.

This is one of the reasons there are MAJOR gaps in my knowledge!

One more gap filled =-)

 

[brucelee]

Hi mate
main switch is jsut a isolator NO LOAD when switched off
a CB is a off load and on load device will switch both under load and not

 

[Darkwood]

Just be cautious here, did you ask in the exact context as you said or were you near a board and you pointed to the main isolation which could have been a rccb main switch which does do protection for overload, i find it as a basic for any tutor but can believe there are sparkies out there that think electric cant flow up-hills as ive met them.
Like the others said a Main Switch is as it is spoken just a switch the rating on the front is its tolerance/loading ability, a front end rcd isn't just a switch but give protection against earth faults but not overload- its rating (A) is also the max load tolerance.