Some more questions

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moonpig

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As i am a man of my word i am back with some more questions for you, again all pretty basic but i want to cover all the bases.

I am curious about the different fixing methods when running cables in masonary walls? :| .

Would i be right that it is best to only run cables in channel if the cable is clipped direct and not chased in?

Would i be right to think that it is best to run cables in oval conduit when the cables are chased into the wall?

To my understanding metal channel is not deemed as mechanical protection and so must only be run in safe zones. Is that right?

To my understanding oval conduit is deemed as mechanical protection. Is that right? Oviously if it is then you can run oval conduit chased into the wall outside safe zones, but the cables are hardly protected (oh well if it complys who am i to dissagree;\)

What the best way to actually fix oval conduit into your chases?

If cable is run in oval conduit then is it de-rated? And so would a ring run in 2.5mm ring now be run in 4mm?

Spurring off a domestic 4mm ring main with 2.5mm complys with the regs yes? but is it a good idea? or should the spur be run in the same size conductor?

Are back to back sockets allowed? (you know when you have a socket on each side of a masonary wall, in different rooms)

Have i covered everything? Is there any additional info you think is worth metioning that i havent asked about? Anyone else got any questions?

Well i reckon that enough for now but i will think up some more and get back to you (hopefully next time with some decent/harder questions:D).

Goodnight all:D, peace out:x.

 

poheZ

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you have an oval conduit issue!

If the mechanical protection is earthed, then it doesnt need an RCD to comply. If you have one circuit in oval then it wont have a grouping derating factor, i dont think you would ever have a space factor issue either.

back to back sockets are a good idea, adding onto a circuit with a smaller size conductor would require you to look at the fuse rating where ever it may be.

and, oh yeah i use capping!

 

SPECIAL LOCATION

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As i am a man of my word i am back with some more questions for you, again all pretty basic but i want to cover all the bases.I am curious about the different fixing methods when running cables in masonary walls? :| .

Would i be right that it is best to only run cables in channel if the cable is clipped direct and not chased in?

Would i be right to think that it is best to run cables in oval conduit when the cables are chased into the wall?

To my understanding metal channel is not deemed as mechanical protection and so must only be run in safe zones. Is that right?

To my understanding oval conduit is deemed as mechanical protection. Is that right?
NO.

Oval plastic conduit, metal capping, plastic capping,

all just provide basic protection against plasters trowels etc.. damaging the sheathing whilst wet plastering a wall.

Oval conduit will make it easier to pull new cables in later...

other than that it can be considered pretty well similar to capping?

Wide capping can have the upper hand where you need to run several circuit cables down a wall, e.g. Above a CU.

Oviously if it is then you can run oval conduit chased into the wall outside safe zones' date=' but the cables are hardly protected (oh well if it complys who am i to dissagree;\)

[/quote']

See above;

Oval conduit or capping metal or plastic Do NOT provide sufficient mechanical protection to prevent nails/screws piercing the cable!

So MUST be in safe zones & (now 17th) be RCD protected.

Or earthed metal conduit!

(unless >50mm which is not practical in many situations!)

Don't get confused with High impact PVC round conduit, e.g. 20mm/25mm

suitable for surface run applications providing reasonable impact protection for garages workshops etc..

What the best way to actually fix oval conduit into your chases?
Any suitable fixing method appropriate for the wall structure and any further covering to be applied.. e.g. plastered over/dry line/damp proof render/batten and wood panel? ; \ :eek: etc..

If cable is run in oval conduit then is it de-rated? And so would a ring run in 2.5mm ring now be run in 4mm?
What load/fuse ratings/circuit length (volt drop/max Zs) are we talking about?

these would be other key governing factors to consider when selecting the CSA of the cables.

Spurring off a domestic 4mm ring main with 2.5mm complys with the regs yes? but is it a good idea? or should the spur be run in the same size conductor?
What is the MCB rating? I assume you are still talking of 32A

Domestic 4.0mm ring are not common on your average size property!

Most domestic rings are in 2.5mm. 4.0mm tend to be radial ccts!

its OK to spur off a 2.5mm ring with 2.5mm & a 32a MCB

so why not spur off a 2.5mm from a 4.0mm with 32a MCB.

Remember spur would only be going to ONE additional accesory...

unless connected via a FCU.

Are back to back sockets allowed? (you know when you have a socket on each side of a masonary wall' date=' in different rooms)

[/quote']

No problem electrically.. there may be physical or structural constraints..

On a single brick internal wall I would stagger any back to back outlets...

or you can end up just knocking a whole straight through the wall with nothing to fix to!!! :( :^O :^O:^O

Have i covered everything? Is there any additional info you think is worth metioning that i havent asked about? Anyone else got any questions?

Well i reckon that enough for now but i will think up some more and get back to you (hopefully next time with some decent/harder questions:D).

Goodnight all:D' date=' peace out:x.[/quote']

think Ive' answered most bits???

someone will pick me up if not! ;) :D
 

cheggers

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the only thing that I can add to your list special is , I would spur off a 4mm ring with 4mm because in the socket that you spurred of would have different conductor sizes in the termination and this could cause problems with the terminal screw not biting the 2.5 as well as the 4mm

another thing it will be a bit tight trying to get 3 x 4mm in one termination it can be done I do it but it is tight.

4mm ring will be the norm soon with insulation in walls and ceilings

 

moonpig

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Cheers guys as usual you have all been very kind and helpful:D.

Specs your are an absolute legend mate;).

Quote:

If cable is run in oval conduit then is it de-rated? And so would a ring run in 2.5mm ring now be run in 4mm?

What load/fuse ratings/circuit length (volt drop/max Zs) are we talking about?

these would be other key governing factors to consider when selecting the CSA of the cables.
I didnt have a particular job in mind i was thinking in general (stupid me), i was thinking along the lines of 'rule of thumb', kind of like a ring would need to be 4mm if run insulation.

Alas we will ust have to come back to it at a later date;) :D .

Quote:

Spurring off a domestic 4mm ring main with 2.5mm complys with the regs yes? but is it a good idea? or should the spur be run in the same size conductor?

What is the MCB rating? I assume you are still talking of 32A

Domestic 4.0mm ring are not common on your average size property!

Most domestic rings are in 2.5mm. 4.0mm tend to be radial ccts!

its OK to spur off a 2.5mm ring with 2.5mm & a 32a MCB

so why not spur off a 2.5mm from a 4.0mm with 32a MCB.

Remember spur would only be going to ONE additional accesory...

unless connected via a FCU.
Sorry mate i did mean fused spur, but i must have forgot to type fusedX(.

Quote:

Are back to back sockets allowed? (you know when you have a socket on each side of a masonary wall, in different rooms)

No problem electrically.. there may be physical or structural constraints..

On a single brick internal wall I would stagger any back to back outlets...

or you can end up just knocking a whole straight through the wall with nothing to fix to!!!
Thats exactly what i was thinking, about it being an issue structurally. Now i know its fine if there staggered;).

think Ive' answered most bits???
I believe you have my good man:D.

Thanks again buddy you have been very helpful.

 

moonpig

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While we are on the subject what do you think about spurs.

My old boss used to hate them (i guess from a testing piont of view), but my new one seems happy enough.

I know there are instances where a fused spur is neccessary, and for just spurs a lot of the there is no other option. But otherwise so long as you stick to the regs (of one is allowed for every socket, unless its a fused spur) do you have an issue with spurs in a domestic property? or fused spurs for that matter? (cant see why you would, but might as well pick your brain while your still willing:D)

Also to go back to 4mm radials do the same regs apply to spurs (obviously when the socket in question is not the final one on the radial circuit), is it still one per socket unless its fused in which case fill your boots?

I take cheggers point about terminating (and agree with it), but would i be right to assume 2.5mm would be ok if spurred or fused spurred form a 4mm radial socket?

 

Apache

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Also to go back to 4mm radials do the same regs apply to spurs (obviously when the socket in question is not the final one on the radial circuit), is it still one per socket unless its fused in which case fill your boots?
I thought you were only allowed spurs of rings not radials?

But I'm not a spark] :)

 

moonpig

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Thats what i am wondering.

Once you know which socket is last on the radial circuit its easy enough to extend the radial, but if the property has all radials and the last socket on the circuit is miles away from where the new socket needs to go a spur would be handy (if it complys that is;) :D ).

 

kme

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Radials can do WHATEVER they like. branch, spur, branch again. You can spur from a spurred spur, or spur from two, three or four different branches ( all at once, if that is what you want.)

The rationalle comes down to this: 32A protective device is higher than the rated capacity of 2.5mm. On a radial, with 16 or 20A protection, the 2.5 is above that capacity generally; so it really doesn`t matter how many branches or spurs there are.

HTH

KME

 

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Radials can do WHATEVER they like. branch, spur, branch again. You can spur from a spurred spur, or spur from two, three or four different branches ( all at once, if that is what you want.)The rationalle comes down to this: 32A protective device is higher than the rated capacity of 2.5mm. On a radial, with 16 or 20A protection, the 2.5 is above that capacity generally; so it really doesn`t matter how many branches or spurs there are.

HTH

KME
Concur entirely Bud...

but... "Radials can do WHATEVER they like"...

bet they cant cook an omelette???? ?:| ; \ ]:) ] :)

:^O :^O:^O:^O

Sorry its that time of day again! ;) :x

As a further illustration for the less technically minded..

Lighting circuits are radials.. you just branch off as & where is appropriate

As KME says... As long as the Cable is a higher rating than the MCB.

obviously taking into consideration.. other practical things such as

floor area covered.

sufficient circuits for convenient distribution & isolation..

expected maximum load on circuit

etc...

 

Apache

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Radials can do WHATEVER they like. branch, spur, branch again. You can spur from a spurred spur, or spur from two, three or four different branches ( all at once, if that is what you want.)The rationalle comes down to this: 32A protective device is higher than the rated capacity of 2.5mm. On a radial, with 16 or 20A protection, the 2.5 is above that capacity generally; so it really doesn`t matter how many branches or spurs there are.

HTH

KME
Fantastic! I need a couple of extra sockets and my house is wired in radials. I have 3 bedrooms upstairs each with one double socket. It's pathetic

 

Mr Sworld

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My place is wired in radials with spurs off spurs off spurs. It might be 'acceptable' but we're sparkie's for gods sake!

Your own pad is the ideal time to wire up that 'ideal electrical install' you've always thought about! :^O

 

Apache

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My place is wired in radials with spurs off spurs off spurs. It might be 'acceptable' but we're sparkie's for gods sake!Your own pad is the ideal time to wire up that 'ideal electrical install' you've always thought about! :^O
Thought 'cobblers' children always worst shod' ;)

 

moonpig

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Radials can do WHATEVER they like. branch, spur, branch again. You can spur from a spurred spur, or spur from two, three or four different branches ( all at once, if that is what you want.)The rationalle comes down to this: 32A protective device is higher than the rated capacity of 2.5mm. On a radial, with 16 or 20A protection, the 2.5 is above that capacity generally; so it really doesn`t matter how many branches or spurs there are.

HTH

KME
It certainly did, thanks mate:D.

 

Mr Sworld

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Sparkies pads....Always too many blo0dy lights left on!!!!!!!!!!! :D :^O:^O:^O:^O
Not now. I've just signed to E-On's green fixed tariff and they give you a free energy monitor.

I now run around everywhere trying to figure out where the extra wattage is coming from!

For example, I am using 262 Watts at the moment which if I used that for 24 hours a day for an entire month would cost me

 

moonpig

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As KME says... As long as the Cable is a higher rating than the MCB.
So on a 4mm 30/32a radial, you could branch off in 2.5mm without there being any problem with the 2.5mm cable branch not being able to carry the same load as the 4mm cable?

 

Apache

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So on a 4mm 30/32a radial, you could branch off in 2.5mm without there being any problem with the 2.5mm cable branch not being able to carry the same load as the 4mm cable?
Thought 2.5mm T&E was rated 24A and 4.0mm 32A, therefore the 2.5mm couldn't carry the load

 

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