Circuit Layout

[jase31]

Socket circuit layout for rewire. I have changed the kitchen ring to 2x 20A radials. Smokes are on the lighting circuit, as it is less likely that this circuit will be isolated than an individual MCB.

Any suggestions, changes or additions welcomed. Has anything been overlooked.

Living Room - 20A Radial - 2.5mm - 3 Double Sockets
Dining Room & Hall - 20A Radial 2.5mm - 5 Double Socket

Bed1 & Bed2 - 20A Radial -2.5mm - 6 Double Sockets
Bed3 & Landing - 20A Radial -2.5mm - 4 Double Sockets

Kitchen Left - 20A Radial 2.5mm 2 Double plus Washing machine & Dishwasher
Kitchen Right - 20A Radial 2.5mm 2 Double plus Tumble Dryer
Freezer - 2.5mm 16A

Oven & Hob - 32A - 6mm

Outside Power - 20A - For future use
Lighting Upstairs - 6A 1.5mm- 5 Lights
Lighting Downstairs 6A 1.5mm- 5 Lights plus porch light plus smokes

All will fit into a 12way Hager CU. Installation method mixed, through joints, and in cable in conduit on a wall.

 

[topquark]

It would help to answer your question if we had a context for the question, is this a proposed CU change/new install etc? Would be useful if you can confirm the cable sizes, method of instalation and design loads.

 

[johnboy6083]

i think you are running in too many circuits mate. why cant all bedrooms and landing be on one circuit? why does the living room have to be on a different circuit to the dining room and hall.Habe a think about the proposed loadings on these circuits, and you willbe able to save yourself some money, time and hassle.

 

[jase31]

i think you are running in too many circuits mate. why cant all bedrooms and landing be on one circuit? why does the living room have to be on a different circuit to the dining room and hall.Habe a think about the proposed loadings on these circuits, and you willbe able to save yourself some money, time and hassle.

Thanks Johnboy,

Think you may be right. There is little load, apart from the kitchen.

Living Room, Dining Room and Hall 20A Radial - 2.5mm - 8 Double Socket
Bed1,Bed2, Bed 3 & Landing - 20A Radial -2.5mm - 10 Double Sockets
Kitchen Left - 20A Radial 2.5mm 2 Double plus Washing machine & Dishwasher
Kitchen Right - 20A Radial 2.5mm 2 Double plus Tumble Dryer
Freezer - 2.5mm 16A
Oven & Hob - 32A - 6mm
Outside Power - 20A - For future use
Lighting Upstairs - 6A 1.5mm- 5 Lights
Lighting Downstairs 6A 1.5mm- 5 Lights plus porch light plus smokes

 

[Dan23584]

Why did you change the kitchen ring to 2 radials?

 

[jase31]

Galley kitchen, run on radial each side, easier than ring due to layout. 40a rather than 32. Could use 4mm 32a radial, but not sure loading warrants it.

 

[ackbarthestar]

I can;t see a problem with running lots of radial circuits, all underloaded. Its very European!

RFCs do keep costs low but don't offer as much earth leakage discrimination, on the condition you use RCBOs and not the cheaper alternative as parallel duel RCDs. It all depends on the size of your clients pocket.

Also, the use of radials in conjunction with DP RCBOs will make it very easy to problem solving at a later date when some numpty plugs in a few leaky appliances.

 

[Knobhead]

I really can’t understand your thinking on this. Six double sockets on a radial doesn’t rest easy with me at all.

 

[Knobhead]

RFCs do keep costs low but don't offer as much earth leakage discrimination.

Why? 30mA is 30mA which ever way it returns to earth.

 

[ackbarthestar]

Why? 30mA is 30mA which ever way it returns to earth.

Spread across different circuits each protected by a separate RCBO?

 

[jase31]

Depending in the design current of the circuit and, the volt drop of the cable and loop impedance, Conventionally, in a domestic situation, a 30A circuit can serve 75 or 100 m2, a 20A circuit 50m2.The regs don't specify numbers of socket outlets because the cable is protected by an appropriate sized breaker

6 Double over Living and Dining room, are likely to run a couple of tvs, DVD, Sky, plug in lamps, being generous no more than 1kw, so still leaves sufficient capacity to plug in higher power appliances. Alternatively, a 4mm radial could be run, with a 32a MCB.

 

[Engineer54]

I really can’t understand your thinking on this. Six double sockets on a radial doesn’t rest easy with me at all.

It's the age of the radial Wonder Electricians. install 3X the amount of circuits that are actually required!! ...Why cause FRC too difficult to test, ...and god forbid trying to fault find on one!!

 

[ackbarthestar]

It's the age of the radial Wonder Electricians. install 3X the amount of circuits that are actually required!! ...Why cause FRC too difficult to test, ...and god forbid trying to fault find on one!!

I've chased faults around RFCs, once using 25kHz pulsed injection equipment. You can have a perfectly sound ring but it might have extended non fused radials. You might have a ring that has interconnections. A small ring with spider connections feeding more than one socket outlet is particularly common in older properties.
Faults on rings are not particularly difficult to find but they do take longer than a single radial circuit. Particularly when you have a damp socket that is causing unwanted tripping of the RCD.
Perhaps the main reason for using lots of radials supplying a limited number of sockets is the reduced inconvenience when a circuit has to be isolated for a period of time, perhaps when you are called at 7pm at night by a confused customer. The solution then is obvious. You don't have to work late but come back at a more convenient time and they can move the appliances over to another socket rather than having half the house without power.

 

[Des 56]

I have to be honest and say that a little bit of free thinking and planning of the design is refreshing to see
So many stick to standard layouts and just install to the standard rather than what they can imagine as superior

How many dwellings do you see that has up lights and down lights,up sockets, down sockets
When these twin rcd boards are used,variation is usefull

Front of the house and rear for instance,both up and down if using a ring
Bedrooms on radials that are on seperate rcds
Instead of an up ring and a down,left side of house and right
Lighting front and back or right and left

Variation on the layout of circuits at least makes good use of the minimal twin rcd installations that are nothing more than a cheap way of complying with what was originally intended by the Iee (if not stated,at least in my perception because it became apparant the public and industry would not bear the cost)that was the widespread use of rcbos for each circuit of a dwelling rather than just a split on the amount of circuits bumped off with one fault

 

[jase31]

Perhaps the main reason for using lots of radials supplying a limited number of sockets is the reduced inconvenience when a circuit has to be isolated for a period of time, perhaps when you are called at 7pm at night by a confused customer. The solution then is obvious. You don't have to work late but come back at a more convenient time and they can move the appliances over to another socket rather than having half the house without power.

There are pros and cons to both. The RFC at a time to reduce copper usage, in days when a entire house may be on one ring (or maybe 2!), using electric heating, and before RCDs and other protection devices were in use. Energy usage has changed, with more appliances and gadgets in use, but generally all low current. The use of multiple radials particularly with RCBO will prevent inconvenience with nuisance tripping esp with it equipment. I still feel that the RFC is of use in a kitchen, where higher loads may be in use, and is easier to wire in 2.5 than a 4mm radial.

 

[Engineer54]

I've chased faults around RFCs, once using 25kHz pulsed injection equipment. You can have a perfectly sound ring but it might have extended non fused radials. You might have a ring that has interconnections. A small ring with spider connections feeding more than one socket outlet is particularly common in older properties.
Faults on rings are not particularly difficult to find but they do take longer than a single radial circuit. Particularly when you have a damp socket that is causing unwanted tripping of the RCD.
Perhaps the main reason for using lots of radials supplying a limited number of sockets is the reduced inconvenience when a circuit has to be isolated for a period of time, perhaps when you are called at 7pm at night by a confused customer. The solution then is obvious. You don't have to work late but come back at a more convenient time and they can move the appliances over to another socket rather than having half the house without power.

Hey don't get me wrong, i have nothing against the use of radial power circuits at all. But an installation design should be based on the needs/requirements of the installation, not on an electricians preference based on his ease of testing, or because of a lack of fault finding skill's on FRC's... Can also be very costly for the homeowner too, all those unnecessary circuits back to the CU!!!

 

[ackbarthestar]

Hey don't get me wrong, i have nothing against the use of radial power circuits at all. But an installation design should be based on the needs/requirements of the installation, not on an electricians preference based on his ease of testing, or because of a lack of fault finding skill's on FRC's... Can also be very costly for the homeowner too, all those unnecessary circuits back to the CU!!!

I agree, the cat can be skinned from the bottom up or from the top down;:wink_smile:.

I install both rings and radials. The preference for kitchens and utility rooms is a ring as stated earlier, but sometimes if an item of equipment I want to keep separate, such as a freezer, I place on its own radial. upstairs Bedroom sockets, where the loading is minimal are usually on radials.

I like the German method of wiring where sub-mains go to each room and power and lighting radials are fed locally, but that's choosing to skin the cat from the side. and is purely personal.