When is a Ring not a Ring ?

[Guffer]

Just been testing some sheltered schemes with lengthy Ring Mains for Corridor Sockets returning high Z's, original install 30+ years using MEM 3871 Type 3 mcb's struggling to meet 80%. Sockets used for low current i.e. Cleaning Equipment, scooter charging etc Replacement mcb's through Eaton £ 70+ each so been replacing with spare 10A mcb's to raise max value.

Can this same method be used if there is a break in the ring thats hard to trace. Surely lowering the mcb size to 20A or 16A takes away the ring requirement as the 2.5mm cannot be overloaded ?

Any flaws with the above ?

 

[telectrix]

problem there is that if you can't find the break, you could be leaving live cable ends floating around. as long as you can make the radials safe. i.e. end each one at a socket, then OK.

 

[johnboy6083]

As tel says

 

[Farmelectrics]

find the break why is so hard to find surely doing continuity tests socket to socket youll find were its broken

 

[sedgy34]

When is a Ring not a Ring ? when its broken or resistance exceeds its 100 mtrs

 

[Amp David]

Is that 100m in length or 100 m squared floor area??

 

[RISElectrical]

A ring is always a ring if wired in a ring configuration, regardless of the MCB supplying it. I recently went to a job that the ring was part wired in 1.5mm cable, wasn't an option to rewire so MCB downrated to suit and recommendation to rewire, however it's still a ring now albeit a 10A ring.

When a ring is more than 100m it is still a ring, it's just a non compliant ring, or so I believe

 

[ian.settle1]

A ring is always a ring if wired in a ring configuration, regardless of the MCB supplying it. I recently went to a job that the ring was part wired in 1.5mm cable, wasn't an option to rewire so MCB downrated to suit and recommendation to rewire, however it's still a ring now albeit a 10A ring.

When a ring is more than 100m it is still a ring, it's just a non compliant ring, or so I believe

A ring can can be longer than 100m, have a maximum area of 100 sq metres and still be compliant as long as the CSA of the cable does not permit the vd to fall below 5% of the supply voltage.

 

[KINKY]

A ring can can be longer than 100m, have a maximum area of 100 sq metres and still be compliant as long as the CSA of the cable does not permit the vd to fall below 5% of the supply voltage.

I thought the reg, about a ring must not cover an area more than 100M squared was done away with?