main switch question

[davesparks]

an mccb main switch then mcb's or mccb's feeding sub boards.

when the shower/sockets/lights trip it doesnt trip every other mcb does it, same thing

No it's not the same thing, you suggested installing a DB and feeding sub mains from MCBs in that DB.
That puts the final circuit MCBs on series with the distribution circuit MCB, this will may not discriminate in the event of a fault on the final circuit.

 

[spark 68]

No it's not the same thing, you suggested installing a DB and feeding sub mains from MCBs in that DB.
That puts the final circuit MCBs on series with the distribution circuit MCB, this will may not discriminate in the event of a fault on the final circuit.

That is what I thought I was replying to earlier, tis Friday night though

 

[davesparks]

You were indeed replying to that, it's post 9 where he said it.

 

[shanky887614]

i wouldn't use either i would use an rccb mainswitch like i was given and told to do on the last job XD

 

[paulthemagpie]

the installation is a 3 phase incoming, however only one the phases used which goes into a henly block then splits into 3.

so best practise would be to place the isolator before the henly block so the main switch covers the whole installtion.

oh and they reasons why the main switch cant be a RCD switch.

 

[Octopus]

the installation is a 3 phase incoming, however only one the phases used which goes into a henly block then splits into 3.

so best practise would be to place the isolator before the henly block so the main switch covers the whole installtion.

oh and they reasons why the main switch cant be a RCD switch.

Do you really need to ask this??

 

[paulthemagpie]

Do you really need to ask this??

do you realy need to ask that?

 

[Plonker 3]

Read 314.1 in the BGB then have a think why you shouldn't fit a RCD main switch on a TN system.

 

[Leesparkykent]

do you realy need to ask that?

Why not?

 

[paulthemagpie]

Read 314.1 in the BGB then have a think why you shouldn't fit a RCD main switch on a TN system.

potentially if we had nuisance triping it could be a killer for this type of business. so rcd protection as a main switch is a no no. RCBO protection for socket circuits is needed so only that circuit in question would disconnect instead of whole supply

 

[Deleted member 26818]

There is no requirement for RCD protection of socket circuits, unless the installation is considered a special location.
Just wondering whether the meter is single or 3 phase?

 

[shanky887614]

yes there is if its under 20amp supply. ill dig reg out of byb later

 

[Deleted member 26818]

yes there is if its under 20amp supply. ill dig reg out of byb later

Good luck with that.

 

[shanky887614]

Good luck with that.

 

[Deleted member 26818]

Thanks for that, as you can see from what you have quoted, there is no requirement for the circuit to be provided with RCD protection.

Socket-outlets are required to be provided with RCD protection, not the circuits supplying them, except in some instances where the installation is considered to be a special location, such as Horticultural or Agricultural.
In fact providing RCD protection for such circuits could be a non-compliance in some circumstances.

 

[shanky887614]

Socket-outlets are required to be provided with RCD protection, not the circuits supplying them, except in some instances where the installation is considered to be a special location, such as Horticultural or Agricultural.
In fact providing RCD protection for such circuits could be a non-compliance in some circumstances.

if the cable is not more than 50mm in wall or has mechanical protection then it needs an rcd

 

[Anthony S]

Exceptions still exist with a risk assessment

 

[shanky887614]

Exceptions still exist with a risk assessment

unless its a dwelling then no you cant skip it

 

[Anthony S]

unless its a dwelling then no you cant skip it

Who mentioned a dwelling ?

 

[Deleted member 26818]

if the cable is not more than 50mm in wall or has mechanical protection then it needs an rcd

Still no requirement for socket circuits to be provided with RCD protection.
Yes there are circumstances where it may be advisable, or the simplest solution to provide RCD protection for such a circuit.
However it still remains that there is no requirement in BS7671 for such circuits to be provided with RCD protection, except in some circumstances where the installation is considered to be a special location.
Doesn't matter whether there is a dwelling involved or not.