Ring or radial in bungalow

[Brightonbill]

I’m rewiring a bungalow and the owner has asked for a radial for all sockets except the kitchen. But there will be a separate washer and dryer in the circuit. Will a 20A radial be enough?

 

[pc1966]

Sorry a bit of additional info. The reason for the radial sockets is that he’s doing all the chasing (great) but wants to minimise it because he’s living there during the rewire

I don't quit grasp this bit, how often do you chase in a groove that is just wide enough and deep enough for a single T&E run?

Surely it is quicker and easier to use one of those multiple blade things to cut something that is wide enough for 20mm conduit and/or two cables?

As other have said, just put in another 20A radial (or two) as needed for the extra current?

 

[Dustydazzler]

Also sometimes trying to make a chase that is barely wide enough to get 1 x cable in it, is just as fiddly to chase . just as messy and just as awkward to back fill afterwards. I have tried and its just a pain in the arse. Might as well do a 1 inch chase and put some proper oval in with 2 cables

 

[westward10]

Are you not getting the irony of this. A radial will require two cables, the same as a ring final apart from the last outlet.

 

[pc1966]

Are you not getting the irony of this. A radial will require two cables, the same as a ring final apart from the last outlet.

And quite probably two runs back to the CU should it need more than 20A

Just a matter of where they run...

 

[pc1966]

There is the option of having hidden JB for each socket, with each one as a branch off the radial, but really the maintenance implications of dozens of JB would horrify me unless all in attic so accessible (not floored, etc, so they are hidden).

 

[nicebutdim]

There is the option of having hidden JB for each socket, with each one as a branch off the radial, but really the maintenance implications of dozens of JB would horrify me unless all in attic so accessible (not floored, etc, so they are hidden).

Not really ideal in a newly wired property.

I don't get why the OP would let themselves be led by an ill-informed client. I find most people are receptive to suggestion, when sound reasoning can be used to back up those suggestions. The small number who can't be talked to tend to make less than ideal customers.

 

[EricMark]

I had a washer and drier on the same FCU for years, and fuse never ruptured, I like the ring due to volt drop restrictions, a ring can have 106 meters of cable max to comply with the 5% volt drop, this assumes 20 amp load at centre and 12 amp even spread.

With the radial the 20 amp is at the end of course, so with a 20 amp overload the maximum length with 2.5 mm is 32 meters, and also it will cost more as you will need three RCBO's instead of one to cover same area. The main problem is in rush, I have had it at work, where we can use a reduced voltage transformer or welding set on a 32A ring, but on a 20 amp radial the overload trips, however unlikely to use those in a domestic.

I am unsure about heat pump driers? Do they have inverters, or are they same as cheap fridge? But would not expect a problem.

To fit a new consumer unit is easy, before you start, you put your clamp meter on the cables, and see what back ground leakage is, but with a new install by time your at a stage where you can measure, it's too late, so only safe way is all RCBO's.

 

[MJPD29]

Sorry a bit of additional info. The reason for the radial sockets is that he’s doing all the chasing (great) but wants to minimise it because he’s living there during the rewire

In what way do you anticipate that minimising it? It eliminates 1 single cable run and severely limits the capacity of the circuit, doubt 4mm will be up to a 32a radial if serving the entire house unless it’s specifically installed to a certain installation method.

 

[telectrix]

Yes. The kitchen to be on a ring, and the rest of the house on a radial (except boiler etc)

so put the washer and dryer on a 4mm 32A radial.

 

[nicebutdim]

so put the washer and dryer on a 4mm 32A radial.

Or pull 2x 2.5 16/20A radials for these appliances.

 

[telectrix]

Or pull 2x 2.5 16/20A radials for these appliances.

but that's 2 cables instead of 1, 2 MCB/RCBOs.. twice the effort and twice more expense.

 

[nicebutdim]

but that's 2 cables instead of 1, 2 MCB/RCBOs.. twice the effort and twice more expense.

Pulling 2x 2.5mm is little more effort than 1x 4mm and cost difference is negligible, but does add the cost of another breaker.

I'm just posting options in a thread that started with a paucity of them.

 

[Pretty Mouth]

This being a bungalow, the cables are likely to be run in the loft, which probably means some derating as they pass through insulation. This probably rules out a 4mm/32A radial. Personally, I'd wire this house as 2 rings.

 

[littlespark]

You choose the best solution for an individual circuit.

A single point… or two close together, then a radial could well be the best option…. But for the rest, where the points are dotted all around, then an rfc.

 

[telectrix]

the only decent form of loft insulation is foam or kingspan between the roof rafters. the 20ft. thick fibreglass needs banning. it's almost as bad as asbestos.