Radials V Ring mains

[MJPD29]

Can you say what these positives are?

Easier to connect, cable is cheaper, and I always struggle to justify how 4mm can be on a 32a breaker unless it's a very short run

 

[davesparks]

I cannot understand how someone can be working on electrics in Canada and not know the voltage is 120v plus or minus 5%. 110v is a myth and outside the permitted tolerance.

I can't understand how you can tell from his post that he was working on the 120V public supply and not a 110V supply for special purposes. Considering the kind of installations Pete has told us he worked on either is clearly possible.

 

[GeorgeCooke]

Are there 110v supplies for special purposes? Would be pretty pointless in a country that has a public supply or 120v.

 

[Pete999]

Hi all,

This may be a common topic and may already have been spoken about 100s of times so forgive me in advance.

I have always wired in ring mains for my sockets up until recently..

I came across an install where all sockets were wired in 2.5 radials protected by 20A RCBO they had wired 3 bedrooms all on separate 2.5 radials (Loft & 1st floor)
i did question why each room was separate and the response i got was "customers request due to computers"

I am hearing more and more people wiring 4mm radials protected by 32A as its "convenient"

whats peoples general thoughts on this?

As long as the 4mm2 Radial complies with 433/1 and Appendix 15 BS7671 I see no problems at all with a Radial wired in 4mm2 protected by either a 30A or 32 A OCPD

 

[Simon47]

I came across an install where all sockets were wired in 2.5 radials protected by 20A RCBO they had wired 3 bedrooms all on separate 2.5 radials (Loft & 1st floor)
i did question why each room was separate and the response i got was "customers request due to computers"

IMO there's a lot to be said for this sort of arrangement - as well as reasons against. It does mean that if one offspring trips the RCD using damaged hair curlers, it doesn't "cause family discord" by tripping off the power to another offspring's gaming rig in the next room, or to dad's servers OK, someone could potentially overload a circuit by plugging in (eg) two fan heaters, kettle's, whatever - but that's just going to trip the overload protection and not damage the wiring, and it's not exactly likely in most homes.
It's going to cost more in RCBOs, but they are coming down nicely in price these days so not likely to be a deal killer as part of the grand scheme.

At our last house I was considering splitting the (single) RFC into two radials - in part because of the difficulty of doing stuff room by room while maintaining the integrity of the ring and not having non-compliant spurs. Haven't determined what to do with the current house yet ...

A an aside, I've seen a new and quite small office wired with what seemed like a ridiculous number of RFCs for the same "because, computers" reason. A couple of jobs (and more years than I care to work out ) ago when I first came across this, I went and measured the earth leakage of a representative sample of our IT kit and found ... nothing significant, definitely no reason to be talking about only using single sockets, high integrity earthing arrangements, and so on.

 

[davesparks]

Are there 110v supplies for special purposes? Would be pretty pointless in a country that has a public supply or 120v.

There may be, without context and details we'll never know for certain. It doesn't seem entirely unlikely that UK government sites in other countries would still use UK 110V tools.

 

[GeorgeCooke]

There may be, without context and details we'll never know for certain. It doesn't seem entirely unlikely that UK government sites in other countries would still use UK 110V tools.

Hm not so sure about that. Not only would it need to be 110v it would need to be 50Hz as well.

 

[telectrix]

IMO there's a lot to be said for this sort of arrangement - as well as reasons against. It does mean that if one offspring trips the RCD using damaged hair curlers, it doesn't "cause family discord" by tripping off the power to another offspring's gaming rig in the next room, or to dad's servers OK, someone could potentially overload a circuit by plugging in (eg) two fan heaters, kettle's, whatever - but that's just going to trip the overload protection and not damage the wiring, and it's not exactly likely in most homes.
It's going to cost more in RCBOs, but they are coming down nicely in price these days so not likely to be a deal killer as part of the grand scheme.

At our last house I was considering splitting the (single) RFC into two radials - in part because of the difficulty of doing stuff room by room while maintaining the integrity of the ring and not having non-compliant spurs. Haven't determined what to do with the current house yet ...

A an aside, I've seen a new and quite small office wired with what seemed like a ridiculous number of RFCs for the same "because, computers" reason. A couple of jobs (and more years than I care to work out ) ago when I first came across this, I went and measured the earth leakage of a representative sample of our IT kit and found ... nothing significant, definitely no reason to be talking about only using single sockets, high integrity earthing arrangements, and so on.

our house, built c.1956 was rewired by my lady's dad in the 80's. being Polish, he did not understand rings, so 2 radial socket circuits wired into a 30A HRC fuse which originally fed a RFC. otherwise, a good install. new CU (fitted my my good self) split socket circuits on to 2 x 20A MCBs. now have the benefit if separation of circuits, RCD protected (except for the garage/man cave with the freezers and workbench)). risk assessment in my addled brain.

 

[davesparks]

Hm not so sure about that. Not only would it need to be 110v it would need to be 50Hz as well.

As I've said, I don't know, but it's not beyond possibility. As far as I know the reverse is also true for US government installations in non US countries, they have 120V 60Hz supplies.

 

[Pete999]

As I've said, I don't know, but it's not beyond possibility. As far as I know the reverse is also true for US government installations in non US countries, they have 120V 60Hz supplies.

Dave, just to add credence to the argument, George seems to be bent on perpetuating, please see below. Some relevant information for you, as if you weren't aware of it already, I was there the voltage was measured at 110 60 Hz we had a Stabiliser at our intake set at a steady state of 110V 60 Hz backed up by a UPs built for us by UK company, no expense spared. Say no more.

american voltage standards - Bing

Intelligent search from Bing makes it easier to quickly find what you’re looking for and rewards you.

www.bing.com