Cables in conduit

[Lectrician]

Why are you set on a ring??

They really should be confined to domestics and small offices etc.

I agree fully with BAN on this. I hate to rings in industrial apps, and HATE to see twonks install 2 or 3 sockets in a ring formation!

If you can't decide which way is best, should you really be doing this install in a factory?

By the sounds of it, you should be installing two radials, one maybe ok in 4mm, but the other may need to be in 6mm. I would throw up some 2x2 galv, and drop from this.

You say you have run 25mm conduit?? Does it have no more than 180deg of bends between draw in points?? Have you used circ boxes, and not crappy inspection tees/bends?? Have you pulled your own bends with a respectable radius where possible?? Have you calculated the cable factor for the conduit?? If you comply with the cable factor, and all the above, pulling in the cables is a peice of ****. The cable factor is by far on the side of caution. AND HAS NOTHING TO DO WITH HEAT - It is the factor used to deterimine who many cables can be drawn in without damage/difficulty.

Are you also aware you can share the earth between circuits, as long as it is sized to the largest circuit??

 

[Emtpencil]

Lectrician

Firstly, everybody has to start somewhere, & perhaps your right, this is my first commercial job, maybe it is too big for me. But I've recently done my time in college, but they dont teach you everything in college as I'm sure you appreciate. Thats why I'm asking, which I thought was the whole point of this website, not just for folk who like to "ram it down other peoples throats" how bl**ding good they think they are !

I am not set on installing a ring, that was my initial plan, but now I know that this seems to be the wrong application, I will re-check my on site guide, check my installation method, diversity, apply correction factors, apply the formula & check the voltage drop....

Thanks for your HELP !

 

[Steve]

ban, what do you propose we start installing instead of ring finals? my personal preference is to have 32A radials - in 4mm² cable.

OR a more European approach, involving 16A radials, and lighting in each room coming off the radial for that room using 3 or 5A FCUs.

The only reason 16A radials are popular in Europe is because they dont have fuses in their plugtops. So everything is protected by a 16A MCB. This is why we can have higher-powered circuits.

And apart from testing, the ring final is a good design - you go around the house from socket to socket, and have no voltage drop at the LAST socket, because it is actually the FIRST socket! Not only that, every DIYer in the country knows what a ring final is, and most DIY books have instructions based on ring finals.

 

[ban-all-sheds]

ban, what do you propose we start installing instead of ring finals? my personal preference is to have 32A radials - in 4mm² cable.

Sounds good to me.

OR a more European approach, involving 16A radials, and lighting in each room coming off the radial for that room using 3 or 5A FCUs.

I prefer separate circuits.

The only reason 16A radials are popular in Europe is because they dont have fuses in their plugtops. So everything is protected by a 16A MCB. This is why we can have higher-powered circuits.

Yup.

Not only that, every DIYer in the country knows what a ring final is, and most DIY books have instructions based on ring finals.

So how come so many of them ***k-up with unfused spurs?

 

[JohnD]

More rings! More rings!

 

[securespark]

Down with Rings! Up the Radials!

 

[Lectrician]

They both have their place, but this isn't it

 

[pdcelec]

Are you within the 75m2 limit?

what 75m2 limit?

 

[RF Lighting]

Radial circuits can only supply a maximum floor area of 75m², wheras rings can serve a floor area of 100m²

 

[pdcelec]

Radial circuits can only supply a maximum floor area of 75m², wheras rings can serve a floor area of 100m²

show me which reg says that and I will accept it. I cannot find one!

 

[supersparky]

its there

anyway, on rewires we dont genrally install rings anymore, prefer to have 2 radials for the kitchen and then divide up/down or left/right or front back into 2 radials minimum or on the odd occasion 2 radials for the kitchen and ring for the house - does away with balencing problems


Dont also forget if you are using a ring in a commercial enviroment and have a socket setup such as this to leap frog the sockets otherwise you will have a stupidly biast ring!!!

got to agree with the above though, 4/6mm radials are always better than rings in commercial

 

[dingbat]

Without appearing thick, & what you've stated in the last comment with people wanting to plug allsorts in during the working day ( diversity ) why is it permissible to install a radial instead of a ring ?

Don't get in a tizzy over this. You design a circuit for the intended load, you choose a protective device to allow this load current to pass continuously and then you choose the size of cable such that the protective device will not allow it to be overloaded. The same applies to radials as to rings, so there is no question of it being permissible or not; it is just another circuit format.

A properly designed radial circuit is easier to install, simpler to extend, less prone to abuse from those with 'a little knowledge' and much, much easier to test. Don't worry about it, do it... you know it makes sense.