Radials V Ring mains

[Octopus]

Give the customer the choice , the prices and the pros and cons and let them decide

 

[buzzlightyear]

I also ran 6mm radials whilst working in Canada @110Volts using MK 110V socket outlets, had nil trouble with connecting them up either

that was the old MK sockets put in them days ,try the new ones ,then you will struggle .

 

[Pete999]

that was the old MK sockets put in them days ,try the new ones ,then you will struggle .

Within the last 10 years Buzz

 

[buzzlightyear]

Within the last 100years Buzz

 

[Baddegg]

Great idea.
20A is plenty for a bedroom and when the kids don't get off the consoles you can switch off the mains to their bedroom.

Have rewired a house before with that exact request for that reason...

 

[Nigel]

All we do is 4mm radials. Easier to wire and less testing.

 

[GeorgeCooke]

I also ran 6mm radials whilst working in Canada @110Volts using MK 110V socket outlets, had nil trouble with connecting them up either. Just saying.

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.

 

[garyt]

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.

Hi check regulations , can use radial 2.5 mm serves 50 square meters 20 amp cb& 4mm at 75 square meters 32 amp cb

 

[ipf]

Just to be a Pedant they are not Ring Mains any more they are Ring Final Circuits or RFCs

Just to be even more pedantic.....and being sick to death of this subject...….I'd go for radial, 1.0mm T+E, 5 amp 3036 and a row of 5amp sockets....

 

[Simon47]

If you think about it, if you take an RFC wired in 2.5 and supplied by a 32A MCB and: remove one section of cable, and split the tails across two 20 or 25A MCBs then you have :

• Increased the total available current from 32A to 40 or 50A
• Reduced the amount of cable used

So the two radials (assuming a new install or a rewire) will need less cable and provide a higher total load capacity than the same outlets wired as an RFC. You've also (assuming RCBOs) reduced the amount of stuff that goes off when a breaker trips.
However, you've also increased the volt drops. So if the alternative RFC was on (or near) the limits, the two radials would most likely be over the limits for volt drops.

 

[Lucien Nunes]

Increased the total available current from 32A to 40 or 50A

However, you have also restricted where the current can be used. With a 32A circuit, regardless of whether it is radial or an RFC, you could spread 32A around half of it, or all of it, and nothing will be overloaded. With two 20A radials, to get even 32A let alone 40A it has to be correctly split between the circuits, which the customer knows nothing about and may not be convenient. E.g. if a room gets flooded and needs drying out, they will plug two heaters and a dehumidifer in there and the 32A circuit would be OK with that, whereas a 20A might trip. I know that's an unusual situation but there are lots of similar scenarios.

This is one of the advantages of the 32A socket outlet circuit that is often overlooked - a larger circuit with more points makes better use of diversity and is less likely to get overloaded if the loads are not in the anticipated places. A typical family home with GCH will run quite happily on a single 32A circuit. Not ideal in the event of a fault etc. but it works fine for loading. Our entire living area used to run fine on one 30A Wylex MCB with lounge, dining room and kitchen including washing machine, tumble dryer, dishwasher, fridge, freezer, microwave etc. Theoretically you can't put just the washer and dryer together on a 20A.

But, importantly, the distinction between 32A circuits and 20A circuits is a different one to the difference between RFC's and radials. The current rating dictates how many circuits are needed, the RFC / radial aspect dictates cable size, testing method etc. A 32A radial provides the same functionality as a 32A RFC.

 

[Simon47]

I agree with all of that. But of course, a 32A radial needs more copper than a 32A RFC.

On overloading radials, at a local church the boiler broke down so they had to use electric heaters - which could barely take the chill off. Of course, someone got over ambitious - and after blowing a fuse (radial on 15A rewirable fuse), told me he'd been careful and plugged them into different sockets He was also amazed that I was able to find the blown fuse

 

[l4urence]

I rarely do final ring circuits now, generally radial in 4mm but watch the cable length.

 

[MJPD29]

I always use rings unless for 1 or 2 dedicated sockets. I find there are far more positives to the ring than a 4mm radial circuit.

 

[Pete999]

I always use rings unless for 1 or 2 dedicated sockets. I find there are far more positives to the ring than a 4mm radial circuit.

Can you say what these positives are?