electric question ( Armoured Cable) outside

21
Found 29th Jan 2015
Hi
Im looking at wiring electric to my out buildings but unsure on which to get?

I want armoured cable from electric box in house to shed with trip switch? And to have few power points for tools and a light,
I also have a summer house at the top of the garden which has cable under ground i put in 2.5mm which i was told was ok as i want a socket up there
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21 Comments
Original Poster
Question is what amp? Or mm cable needed?
Would 2.5mm SWA Steel Wire Armoured Cable do?
sme24185

Question is what amp? Or mm cable needed? Would 2.5mm SWA Steel Wire … Question is what amp? Or mm cable needed? Would 2.5mm SWA Steel Wire Armoured Cable do?


2.5mm will be fine if protected with RCD. Google RCD.
sme24185

Question is what amp? Or mm cable needed? Would 2.5mm SWA Steel Wire … Question is what amp? Or mm cable needed? Would 2.5mm SWA Steel Wire Armoured Cable do?



Make sure you buy 3-core , buying 2-core and relying on the armouring as an earth is not advisable.
2.5mm will not be fine. An RCD only detects earth faults, you'd need a separate/combined MCB which will trip in the event of overload. However, 2.5mm isn't big enough for a radial circuit, put in at least 4mm if not 6mm and then you'll be futureproof as well.
I should have added, get an electrician in!!
Hallsie

2.5mm will not be fine. An RCD only detects earth faults, you'd need a … 2.5mm will not be fine. An RCD only detects earth faults, you'd need a separate/combined MCB which will trip in the event of overload. However, 2.5mm isn't big enough for a radial circuit, put in at least 4mm if not 6mm and then you'll be futureproof as well.



The op will have overload protection on the cable installed at his house consumer unit - the 2.5mm cable is protected by a 32a mcb, there is also a stong possibility his house consumer unit will have 30mA residual current protection thus also protecting the cable.

The only reason he needs to install a bigger cable as you suggest is for volt drop purposes, the op has not stated how much cable he needs.......

In his shed he will need a 2 way consumer unit fitted with 6amp and 16 amp single pole mcbs plus either an rcd or double pole switch depending on his house consumer unit.
Edited by: "transit" 29th Jan 2015
2.5mm swa use a 20a fuse
4mm swa use 32a fuse (better)
ho5dow

2.5mm swa use a 20a fuse4mm swa use 32a fuse (better)



2.5MM Cable is rated up to 32a.
Original Poster
Hi thanks
if i remember 2 years ago i was asking the question, if i remember now they said 4mm upto shed 25m- 30 in to a comsumer box then from that the 2.5mm from shed up the yard to summer house again 30m ish in cable
transit

2.5MM Cable is rated up to 32a.




please check online 'ring main' and 'radial'
32a for a 2.5mm ring main
20a for 2.5mm radial
Edited by: "ho5dow" 29th Jan 2015
sme24185

Hi thanks if i remember 2 years ago i was asking the question, if i … Hi thanks if i remember 2 years ago i was asking the question, if i remember now they said 4mm upto shed 25m- 30 in to a comsumer box then from that the 2.5mm from shed up the yard to summer house again 30m ish in cable



That sounds fine.
ho5dow

32a for a 2.5mm ring main20a for 2.5mm radial



Wrong, 32a for swa xlpe cable!

I don't need to check online i install the stuff on a daily basis.
Edited by: "transit" 29th Jan 2015
transit

Wrong, 32a for swa xlpe cable!I don't need to check online i install the … Wrong, 32a for swa xlpe cable!I don't need to check online i install the stuff on a daily basis.


thanks
learn something new from here.
ho5dow

thankslearn something new from here.



No problem.
Original Poster
Ok thanks ill price up the 4mm not 2.5
Thanks
Get a consumer unit with rcbo, not rcd then you are covered for all eventualities. Then install 4mm swa xple.
In your shed get a mini consumer unit to separate your lights from your power tools.
Look at 17th edition for burying the cable, there are requirements to not just surface lay it or bury it 10mm, cant remember off the top of my head.

How long is your run?
Voltage drop calcs apply...
Trunking, grouping cables etc change your calcs again. Do your research and you'll prob find 2.5mm not up to the job.

Ps I'm an electrical engineer in a very dangerous industry so I know what I'm.talking about
gr8t1

Get a consumer unit with rcbo, not rcd then you are covered for all … Get a consumer unit with rcbo, not rcd then you are covered for all eventualities. Then install 4mm swa xple.In your shed get a mini consumer unit to separate your lights from your power tools.Look at 17th edition for burying the cable, there are requirements to not just surface lay it or bury it 10mm, cant remember off the top of my head.How long is your run?Voltage drop calcs apply...Trunking, grouping cables etc change your calcs again. Do your research and you'll prob find 2.5mm not up to the job.Ps I'm an electrical engineer in a very dangerous industry so I know what I'm.talking about



Advising the Op to install an rcbo is pointless without knowing if his existing consumer unit is rcd protected, an rcbo will have a 30mA trip as will his existing rcd....... there will be no discrimination between the two and a total waste of money.

The op needs to get a qualified spark to do work and let the spark decide as per the existing installation.


P.S. I work as an Electrical Supervisor in the construction industry.
Wrong
Because an rcbo will give overload protection as well as current imbalance thus resolving points made earlier in the post..
I work as a chef, run the cable through some hose and bury 6" underground from your house to the shed.

PS in another life I was a navy seal.
gr8t1

WrongBecause an rcbo will give overload protection as well as current … WrongBecause an rcbo will give overload protection as well as current imbalance thus resolving points made earlier in the post..



Lol I try my hardest not to give advice on here to the unqualified and when i do i'm as vague as i can be for a reason........... maybe i've been doing my job wrong for umpteen years oO


Ps My dad is bigger than your dad oO
My dad is dead so yes he probably is
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