Garage mains wiring query ??

[Heatslave]

Hi ,

Confident and competent DIY'er here with a query about my garage mains, hope someone can help please ??

I had an extension done a couple of years ago, and part of that was a new garage. The qualified electrician did all the wiring, including a new fuse box which lives in the garage. There are 3 x 240v double sockets and I wanted to add a new double socket, so I was checking the the wiring the electrician did. To me, the three double 240v sockets don't look to be a ring main. To me it looks like they are all spurs (see attached diagram) ??

Can I just add another spur, or would it be better if the whole thing was on a ring ?? All sockets would probably never all be in use at the same time.

Cheers

 

[opps]

Based on your image he has run two additional spurs off a spur. Not allowed

Perhaps run a leg back to the "fuse box".

I am not an electrician though.

 

[blup]

Are they spurs, or on a radial in which case should be ok to extend

 

[JohnW2]

Based on your image he has run two additional spurs off a spur. Not allowed

The first one is certainly not a spur. What the OP has drawn is simply a radial. However, whether or not it's OK depends entirely on the rating of the circuit's OPD in the 'fuse box' and the size of cable.

 

[Heatslave]

The first one is certainly not a spur. What the OP has drawn is simply a radial. However, whether or not it's OK depends entirely on the rating of the circuit's OPD in the 'fuse box' and the size of cable.

hi John,

Thanks for the reply.

Can you be @rsed to briefly explain a “radial” please, and how it’s ok in this situation ?? And how, if everything is rated ok, another spur can be added ?? (All wires are standard ring main 2.5mm twin and earth)

Attached is a pic of the circuit breaker in off position

 

[Heatslave]

Are they spurs, or on a radial in which case should be ok to extend

Having googled it, it is indeed on a radial circuit . A new one on me, I thought it had to be a ring

 

[opps]

The first one is certainly not a spur. What the OP has drawn is simply a radial. However, whether or not it's OK depends entirely on the rating of the circuit's OPD in the 'fuse box' and the size of cable.

Point taken. And it looks like the OP is on a 16 amp MCB, which means, that yes, it is permissible, but it is far from ideal if the OP plans to run two devices running at 13 amps simultaneously.

That said, yes, I was incorrect.

 

[EFLImpudence]

Having googled it, it is indeed on a radial circuit . A new one on me, I thought it had to be a ring

On the contrary; every circuit is a radial apart from the anachronistic UK sockets ring circuit - devised for special circumstances after WW2.

 

[JohnW2]

Can you be @rsed to briefly explain a “radial” please, and how it’s ok in this situation ??

Noi problem. A radial circuit is simply what you have drawn - a circuit which starts at a fuse or breaker in the fuse box/CU and which goes 'fromsocket to socket. Unlike a 'ring' ('ring final circuit') there is not a connection from the last socket back to the CU. Radial circuits can also 'branch'.

Rings appeared, virtually only in the UK, just after WWII, allegedly due to a shortage of copper, and have persisted (only in UK). Almost everone else uses just radial circuits, and they are very much coming back into vogue even in the UK.

Your circuit is protected by a 16A MCB. That being the case, everything is fine, with any credible size of cable used to wire the sockets. 2.5mm is certainly fine..

And how, if everything is rated ok, another spur can be added ?? (All wires are standard ring main 2.5mm)

Yep, you can add as many extra sockets you like, originating them at any one of the existing sockets, and even having a 'string'; of them idf you want. However, be aware that the total load across all of your sockets will be limited to 16A (about 4kW) by the 16A MCB in your CU.

Hope that helps.

Kind Regards, John

 

[Heatslave]

Point taken. And it looks like the OP is on a 16 amp MCB, which means, that yes, it is permissible, but it is far from ideal if the OP plans to run two devices running at 13 amps simultaneously.

That said, yes, I was incorrect.

I think it’s more my non electrician explanation of things that confused the matter, not you being incorrect . I appreciate the reply

And just for info, the washing machine and tumble drier are in use on one of the double sockets, but are never used at the same time, and would not be in use at all if I was using the other sockets for DIY, etc, now I know they’re on a radial circuit.

 

[JohnW2]

And just for info, the washing machine and tumble drier are in use on one of the double sockets, but are never used at the same time, and would not be in use at all if I was using the other sockets for DIY, etc, now I know they’re on a radial circuit.

One of the machines at a time would certainly be fine. In practice, so would having both of them on simultaneously, even though that is pushing things a bit for a 16A circuit. It's the dryer which is the energy-guzzler - a WM only draws high current for a pretty short period of time (whilst it's heating water), not long enough to be a problem

 

[Heatslave]

Noi problem. A radial circuit is simply what you have drawn - a circuit which starts at a fuse or breaker in the fuse box/CU and which goes 'fromsocket to socket. Unlike a 'ring' ('ring final circuit') there is not a connection from the last socket back to the CU. Radial circuits can also 'branch'.

Rings appeared, virtually only in the UK, just after WWII, allegedly due to a shortage of copper, and have persisted (only in UK). Almost everone else uses just radial circuits, and they are very much coming back into vogue even in the UK.

Your circuit is protected by a 16A MCB. That being the case, everything is fine, with any credible size of cable used to wire the sockets. 2.5mm is certainly fine..


Yep, you can add as many extra sockets you like, originating them at any one of the existing sockets, and even having a 'string'; of them idf you want. However, be aware that the total load across all of your sockets will be limited to 16A (about 4kW) by the 16A MCB in your CU.

Hope that helps.

Kind Regards, John

That’s a great reply, thanks for the info

I just didn’t want the electricity to run out at the last socket (I know, a poor non electrician joke )

Thanks for the reassurance, much appreciated

 

[Heatslave]

One of the machines at a time would certainly be fine. In practice, so would having both of them on simultaneously, even though that is pushing things a bit for a 16A circuit. It's the dryer which is the energy-guzzler - a WM only draws high current for a pretty short period of time (whilst it's heating water), not long enough to be a problem

Cheers, now I know what’s going on electrical wise, I’ll be careful what I’m using at one time

 

[JohnW2]

I just didn’t want the electricity to run out at the last socket (I know, a poor non electrician joke )

That reminds me of something that a so-called electrician tried to tell me (just before I showed him the door) - but it's a story I've told many times here

Thanks for the reassurance, much appreciated

You're welcome

 

[SUNRAY]

On the contrary; every circuit is a radial apart from the anachronistic UK sockets ring circuit - devised for special circumstances after WW2.

Ring circuits appear all over the place apart from the regular 32A ring final and rings were in use decades before WW2.
Oh and excuse the quality of the tester and photo but this is a 6A lighting ring.