Cable sizing help required

[sparkykarl]

Hi Guys,

i'm currently in the process of quoting for a job I hope to win. I need to work out the size of cable required to supply 20 studio flats.

i am going to run a supply or several supplies from the basement of the building 16m up an lift shaft then will be approximately 40m through a ceiling to an isolator/s size of which is unknown at this stage. Then from the isolator/s to a three phase distribution board or more then from those boards to 20 top up electric meters then off to each studio flat with 16mm Twin and Earth.
pAny help would be helpful

Karl

 

[Ohm4]

So each flat will have its own meter and billing address?
In my limited experience the electricity board for that area will supply and run cables from the main supply to the meters. They don't like you touching anything past the main feed to the property.
Someone will clarify soon enough!

 

[Ohm4]

Ah I read it wrong or miss understood (maybe) but surely the cable will have to be 16mm armoured or bigger.

 

[sparkykarl]

I need a cable size or if I need to use more then one from the main supply in the basement of the mill that is been converted. To an isolator of which will supply a 3 phase DB or more then one which will then supply each studio of which the studios will have a 63a max load

 

[sparkykarl]

Twin and earth would be fine as the cables are been run through false ceiling in free air

 

[Darkwood]

No your not going to run it up a lift shaft! ...... know your reg's 528.3.5

Even redundant lift shaft must get written permission that they will never be converted back .... these regs you should already know!

 

[sparkykarl]

I am just going on the words of the building contractor

 

[Darkwood]

He's a building contractor enough said you are the electrician you are the one to inform him you can't do that, only a written AI (architech instruction or similar) with local electrical clark of works input would get you around this and that IMHO won't happen .... dont let the cart lead the horse ... you trained in college to not only to do your job but to correct the ill educated when you are requested to do something..... if he argues walk away this is a very strict regulation and anyone ignoring it could find themselves indeep doo doo!

Sorry for the bluntness of my reply but it could get you in alot of trouble and im supprised at other posters carrying on the theme without pointing this out.

 

[sparkykarl]

Point noted but could you help me with the cable sizing. I'm thinking 240mm 4 core armoured would suffice

 

[Darkwood]

Its my bedtime but this is obviously out of your comfort zone .. 240mm cable supply would be associated with a very large industrial install you will have loads of fun pulling that in and deffo wont win on the pricing..... if you are out of college with a basic Electricians rating you really need to go and do the advanced design courses before undertaking this work, you may get hints and tips on here but any mis-info or lack of info could get you the wrong advice and cost you dearly...... Diversity is the key word here!

 

[Engineer54]

Its my bedtime but this is obviously out of your comfort zone .. 240mm cable supply would be associated with a very large industrial install you will have loads of fun pulling that in and deffo wont win on the pricing..... if you are out of college with a basic Electricians rating you really need to go and do the advanced design courses before undertaking this work, you may get hints and tips on here but any mis-info or lack of info could get you the wrong advice and cost you dearly...... Diversity is the key word here!

I'm almost frightened to even suggest thinking along the lines of a parallel supply feeder!! lol!!

Your earlier comments on using the lift shaft as part of this cable route is well founded, and i'm also surprised that no-one else picked up on this too!! There are also other electrical factors to be taken into consideration if this lift shaft is now redundant, not only electrically speaking, but fire/building codes too!!

 

[bigbaddave]

240mm cable up an elevator shaft...... Your got the Rock and Arnie Swarts working for you???

 

[Darkwood]

I'm almost frightened to even suggest thinking along the lines of a parallel supply feeder!! lol!!

Your earlier comments on using the lift shaft as part of this cable route is well founded, and i'm also surprised that no-one else picked up on this too!! There are also other electrical factors to be taken into consideration if this lift shaft is now redundant, not only electrically speaking, but fire/building codes too!!

Hence i stipulated special permissions would be required even if redundant as fire safety is one of the original reasons behind the regulation in the first place lift or no lift in shaft..... Thinking busbar riser for this building but lack info ....in this case he should be able to apply a diversity factor between the 20 studio's as they all wont be high demand together after hes calc' the demand of each studio.

The redundant lift shaft comment was a stab n the dark as im dumbfounded the building contractor even considered this .... i take it this is a private building contractor and not a full contracted install with foreman, architect and clark of works.

 

[Engineer54]

To be honest, i lost interest when he stated using T&E as his intended tails to the individual apartments/studio's!!

 

[bigbaddave]

I remember when i was young and learning to ride a bike..

My mam allways had a certain phrase she said to me time and time again when i was impatient..

Oh yes... Dont try and run before you can walk..