Can ring circuit be bigger than 32A with bigger cable size??

[King84]

Hi everyone

my questions is regarding a ring circuit wired in 2.5mm standard twin n earth with 32A MCB however my question is hypothetical if there are 2 laundry and 2 lets say tumblers so load is not suitable for the circuit and you want to upgrade but there is no space in consumer unit to accomodate the new circuit
Can you upgrade ring circuit to bigger cable size such as 4 mm and then use a bigger circuit breaker such as 40 .
This is scenario in one of NHS hospital where electricians were thinking about upgrading it and I have been told this by one if my friend who is assistant in NHS and I have never come across this kind of question so would love to know how this should be tackled ??

 

[Rockingit]

This is where the BBB fails us. Theoretically, absolutely (although issues of ratings of accessories becomes something to look at). The national grid is basically one giant RFC. The problem is that RFC's are only ever referred to in the book as coming off of a 30A or 32A CPD (App 15). I've got a session with my NICEIC engineer on Monday, I'll ask his take on it.

 

[Marvo]

One problem that immediately springs to mind if your using flat twin cable could be inadequate CPC size. As Rockingit says, in theory there isn't a limit to the ring final circuit size but I'm not sure whether your UK regs would permit

 

[westward10]

If the circuit incorporates accessories complying to BS1363 then according to Regulation 433.1.204 no you can not.

 

[Spoon]

Just for ref:

433.1.204 Accessories to BS 1363 may be supplied through a ring final circuit, with or without unfused spurs, protected by a 30 A or 32 A protective device complying with BS 88 series, BS 3036, BS EN 60898, BS EN 6094 7-2 or BS EN 61009-1 (RCBO). The circuit shall be wired with copper conductors having line and neutral conductors with a minimum cross-sectional area of 2.5 mm2 except for two-core mineral insulated cables complying with BS EN 60702-1, for which the minimum cross-sectional area is 1.5 mm2• Such circuits are deemed to meet the requirements of Regulation 433.1.l if the current-carrying capacity (lz) of the cable is not less than 20 A and if, under the intended conditions of use, the load current in any part of the circuit is unlikely to exceed for long periods the current-carrying capacity (Iz) of the cable.

 

[Lister1987]

Just for ref:

433.1.204 Accessories to BS 1363 may be supplied through a ring final circuit, with or without unfused spurs, protected by a 30 A or 32 A protective device complying with BS 88 series, BS 3036, BS EN 60898, BS EN 6094 7-2 or BS EN 61009-1 (RCBO). The circuit shall be wired with copper conductors having line and neutral conductors with a minimum cross-sectional area of 2.5 mm2 except for two-core mineral insulated cables complying with BS EN 60702-1, for which the minimum cross-sectional area is 1.5 mm2• Such circuits are deemed to meet the requirements of Regulation 433.1.l if the current-carrying capacity (lz) of the cable is not less than 20 A and if, under the intended conditions of use, the load current in any part of the circuit is unlikely to exceed for long periods the current-carrying capacity (Iz) of the cable.

So reading between the lines you COULD do a ring on larger cables and utilise Ceeform plugs/socket and any others that aren't 1363?

 

[Spoon]

So reading between the lines you COULD do a ring on larger cables and utilise Ceeform plugs/socket and any others that aren't 1363?

I'm presuming you wouldn't find may Ceeform plugs/sockets in a domestic setting, except for in the garage. Welders and such...

 

[westward10]

It's a hospital laundry.

 

[Spoon]

It's a hospital laundry.

I forgot about that bit.. ??