Fuse and Ringmains

[ewand]

Is it ok to have two ringmains going into the same fuse in the central fuse box? In otherwords, 4 wires? Thanks folks.

[BillyNoMates]

Absolutely not - even if the correct circuit protection rating is used (I.e. 30 or 32A). Whilst it would work, there are limitations on the recommended area served by a domestic ring main - 100 sq metres, you could also exceed the maximum demand of the protective device.

If the protective device trips, you will lose both rings. And many other good reasons.

[ewand]

Thanks BillyNoMates, so would you carry on the upstairs ring main? Essentially, I have a upstairs ringmain and a downstairs stud into the same fuse. I intended to change the stud into a secondary ringmain, as I believed that was safer than just having a stud?

[BillyNoMates]

Not sure I understand what you mean by stud ? Study ? Are you just wanting to add more sockets to an existing ring ?

The general rules are - maximum floor area of 100 sq metres per ring (in theory as many sockets as you like). Look at the diversity and ensure that the maximum potential load won't exceed the rating of the protective device.

Kitchens should ideally be on a separate ring. You could consider a radial circuit. There are also rules regarding the number of unfused spurs and fused fixed appliances off a ring.

[ewand]

Ha.....sorry I meant SPUR! (quite why stud was on the brain I don't know!)

[BillyNoMates]

OK - well you are allowed spurs on the ring up to the number of directly connected sockets and directly connected fixed appliances. I wouldn't personally recommend going to these maximums but those are the rules.

Each spur should feed no more than a single or double socket or one fixed appliance.

Basically look at the potential load and decide whether to split into a separate ring with a separate fuse/breaker at the board.

Hope that helps.

[BillyNoMates]

PS. If you are going to separate the spur and take it back to the board it is then a radial circuit and needs a separate 20A breaker.