Shower Cable

[cprfenom]

So its the route of the cable that defines that its a ring or a parallel circuit??

 

[DPG]

So its the route of the cable that defines that its a ring or a parallel circuit??

Not entirely no. Daz

 

[baldsparkies]

Remember what I said at the end of my post !!
Yea but no but yea but lol.

So you have two 2.5 cables feeding a single double socket on a 32 amp mcb
Is it a ring main, or a radial with two 2.5 feeds ??

And here we go again lol
Yea but no but yea but.

 

[Leesparkykent]

Remember what I said at the end of my post !!
Yea but no but yea but lol.

So you have two 2.5 cables feeding a single double socket on a 32 amp mcb
Is it a ring main, or a radial with two 2.5 feeds ??

And here we go again lol
Yea but no but yea but.

what do you think? Lol

 

[Marvo]

..........So you have two 2.5 cables feeding a single double socket on a 32 amp mcb
Is it a ring main, or a radial with two 2.5 feeds ??........

If the cables were identical lengths and running the same route it could be called either in theory....but if you called it a parallel cabled radial you could put a 40A MCB on it whereas if the mood took you to call it a single socket ring final you'd only be able to put a 32A MCB on it

 

[baldsparkies]

Ok, how about if the two 2.5mm cables on a 32A mcb supply and distribute power to socket outlets, as opposed to either fixed load equipment, or designated as a sub main.
By definition it would be considered a ring main supply.

So the deciding factor is the looped cable is distributing power to socket outlets.

And can somebody please help the OP to wire his damn shower in 10mm cus this is all getting very ---- lol

 

[Marvo]

I quite like the thread, it's one of those where you immediately get the knee jerk reactions for no other reason that it's just not common practice, same as you get with the guys who would never ever run neutrals through switches......just because it isn't done that way. Then after some probing questions it transpires there's nothing in the regs to prevent it, in fact there's specific guidance in the regs about parallel cabling of circuits and the line between a parallel cabled radial circuit and a ring final circuit with a single socket outlet on it aren't crystal clear either.

All that said it's pretty unlikely I'd ever supply a domestic shower using a parallel cabled radial cct or a single outlet ring cct for that matter.

 

[Risteard]

To me two cables running to one socket outlet, which follow the same route etc. would be a parallel circuit and not a ring final circuit, as the conductors do not form a ring. It would also be quite idiotic for one BS 1363 socket outlet. I have seen it done before and frankly I cringed.

 

[andyb]

Interesting thread, for what it's worth here's my tuppence worth.

I would say it's a ring.

If it is a radial of two 2.5s in parallel and you wanted to wire another socket from the one existing socket you would need to run another 2 x 2.5s to the new socket.
I'm not sure that this would be done. If it's a ring then you can take a single 2.5 from the existing socket to the new one.
I'm sure that anyone coming after you would do this.

Just an opinion.

 

[Marvo]

To me two cables running to one socket outlet, which follow the same route etc. would be a parallel circuit and not a ring final circuit, as the conductors do not form a ring. It would also be quite idiotic for one BS 1363 socket outlet. I have seen it done before and frankly I cringed.

It's probably more likely to occur when sockets have been removed from a ring circuit just leaving one remaining in which case the two cables would likely be different lengths and following different routes so it wouldn't qualify as a parallel cabled radial so it would have to be considered an rfc.

 

[Risteard]

It's probably more likely to occur when sockets have been removed from a ring circuit just leaving one remaining in which case the two cables would likely be different lengths and following different routes so it wouldn't qualify as a parallel cabled radial so it would have to be considered an rfc.

I find the most usual case is that some people bizarrely assume that sockets must be wired as a ring and therefore bring a parallel feed to one socket, e.g. in a garage.

 

[Guest77]

I'd be interested to know if there's actually a reg that forbids it in the UK, I know there isn't in our domestic regs. As said already, it's common practice with cables in larger distribution networks but the logistics of ensuring identical lengths, routes and connecting a parallel cabled domestic final circuit would make it a bad idea.

Didn't know you had showers in those straw/mud huts over there Marv.

 

[Marvo]

I find the most usual case is that some people bizarrely assume that sockets must be wired as a ring and therefore bring a parallel feed to one socket, e.g. in a garage.

Yeah, there's many who do things in a certain way without questioning things just because it's the norm or that's the way they were taught and TBH I don't think even the setup suggested in the opening post would be out of the question if all the implications were taken into account before doing it. There could in theory at least be certain times and places where a parallel cabled radial might be an option.

Another consideration that nobody mentioned yet might be cpc sizes and disconnect times, especially with 4mm flat twin which only has a 1.5mm cpc, there might be occasions when 2x parallel 2.5mm cables would give better disconnect times. Just a thought.

 

[Marvo]

Didn't know you had showers in those straw/mud huts over there Marv.

I'll have you know I live in the posh end of Africa

 

[Risteard]

That's the limitation of 4mm^2 T&E indeed. Adiabatic expressions might need to be considered. Other than 1mm^2 T&E all sizes have a reduced csa.

But if he had 2 * 4mm^2 in parallel then it's unlikely to be an issue, given that 10mm^2 T&E would only have a 4mm^2 cpc anyway.

Although BS 7671 does not prohibit the arrangement, some jurisdictions do not permit parallel circuits for final circuits but only for distribution circuits. And in reality, there generally isn't any reason to do it with a final circuit.

 

[Flanders]

I think the main issue when dubbling up cables in this senirio is being able to terminate he cable correctly within switches and the shower, without to much of the copper showing as we all know unless you use a crabtree pull cord its quit difficult to connect the two 6mm into those square 45amp pull cords so as i said betore connecting the 4 cables may be a bit of challenge, cone to think of ut i dont think you could get 2 sets of 4mm into a crabtee pullcord either