Any thoughts on this....

[sythai]

Have a domestic customer that has part of a ring supplying a study area.

An he wants to have this extended in dado to include an additional 10-15 double sockets. To be used for computers, printers, mointers etc.

But he would like to be able to isolate these extra sockets at one point, a 'last man out switch' sort of thing.

Simples if this was a dedicated ring but it covers another room that will need to stay on.

Cant run any extra circuits/ legs in as he dosent want any floors up etc....

Only way I can think of doing this is by installing 2/3 x switched fused spurs each one supplying 5 x sockets ?

Or maybe is there a way I can make up some sort of contactor unit...?

Any thoughts please or better solutions ?

Many thanks,


Sy

 

[sythai]

Thanks Greg..... does look like a good product, bet its pretty pricey ££

After all that the customer is going to stick with no seperate isolation, makes my job a bit easier..

Thank you for all your feedback,

Sy

 

[Johno]

If it's only supplying computer, printer, scanner etc then you might get away with 1 x 13A SFCU

 

[jase]

So would I be right then thinking I may be able to do it like this....

45a DP isolator, ring in and out on feed side, then off load side run a 4mm radial ?

You would then be spurring ALL the additional sockets from one point of the ring circuit thereby massively overloading the ring circuit at this one point....a big no no IMO.

i agree lenny, isnt this exactly what would be happening if you ran a mainline track off of the ring ??? ie, the mainline track would be a spur upon which the customer could put as many points as he wants, no no no!!!!

 

[Johno]

The ring shouldn't be overloaded (as obviously on 32A MCB), but it isn't something I would feel comfortable doing as it's not a ring nor a radial, it would just make a mess of the existing installation, and you would have to add an extra sheet to the cert saying what you had done.

What is going to be plugged in? surely a little office in someones house doesn't require much power.

 

[jase]

The ring shouldn't be overloaded (as obviously on 32A MCB), but it isn't something I would feel comfortable doing as it's not a ring nor a radial, it would just make a mess of the existing installation, and you would have to add an extra sheet to the cert saying what you had done.

What is going to be plugged in? surely a little office in someones house doesn't require much power.

no power atall. the op wants a way of extending the ring but only isolating the office which would be on that ring

 

[jase]

i am thinking something with contactors, NO,NC so that the office is part of the ring when the contactors are energised???

 

[jase]

nope, got it, split the ring into 2 A3 radials, then put in 20 amp double pole switch where feed to office comes in

 

[buzzbar4]

Hmmm are we going away from the rule book here? hard wiring unprotected contactors and radials into a ring main, a D/P switch fuse, tripped at 20 off both legs, coming out with 4s for your radial would be a better option, why use a contactor at all? or keep to your original idea with your three spurs nothing wrong with that.

 

[SirKit Breaker]

How about breaking into the ring, taking a spur to a Switched fused spur (RCD or not as the install needs). From the spur run a 2.5mm radial to feed your sockets. This is compliant even though you are in effect spurring from a spur etc, but you have protected your circuit from overload because your fused spur is limiting your new leg to 13a. Not an Ideal solution i know, but will get you out of a corner. If you do take this option, make sure your Zs is in spec at last point of the circuit extension. You would be in effect making a long extension lead.

Cheers.........Howard