Armour cable suitable

Is 10m armoured of sufficient kva

  • 12

    Votes: 2 100.0%

  • 12

    Votes: 2 100.0%

  • 12

    Votes: 2 100.0%
  • Total voters
    2
B

Bigacey

New Member
Need a 23 metre run of armour cable from house consumer unit with added isolater box to garage
10 feet will be run across hall concrete floor chased 35 mm wide 35 mm deep ,to gable end of house rest will be buried
Very little additional power needed except a single phase mig welder , 4 overhead led lights , cut off saw and angle grinders but of course these will not be operated if welding
My thoughts are 10 mm 3 core armoured cable the garage already been retired has a new metal consumer unit fitted by an electrician
I have an electrician going to wire both ends but I hope to have the cable in ready
 
What calculations have you carried out?
Have you asked the electrician as that is the most obvious person to ask.
I don't understand the answers or question to your poll.
 
Agreed - the poll makes no sense.

10mm SWA for 23m to supply sockets and lights is huge overkill. The issue will be the Mig welder. What can you tell us about the requirements for the welder ?
 
Bigacey said:
Need a 23 metre run of armour cable from house consumer unit with added isolater box to garage
10 feet will be run across hall concrete floor chased 35 mm wide 35 mm deep ,to gable end of house rest will be buried
Very little additional power needed except a single phase mig welder , 4 overhead led lights , cut off saw and angle grinders but of course these will not be operated if welding
My thoughts are 10 mm 3 core armoured cable the garage already been retired has a new metal consumer unit fitted by an electrician
I have an electrician going to wire both ends but I hope to have the cable in ready
Click to expand...
Bigacey said:
10 feet will be run across hall concrete floor chased 35 mm wide 35 mm deep
Click to expand...

I'd go deeper:cool:
 
WH55 said:
Agreed - the poll makes no sense.

10mm SWA for 23m to supply sockets and lights is huge overkill. The issue will be the Mig welder. What can you tell us about the requirements for the welder ?
Click to expand...
WH55 said:
Agreed - the poll makes no sense.

10mm SWA for 23m to supply sockets and lights is huge overkill. The issue will be the Mig welder. What can you tell us about the requirements for the welder ?
Click to expand...
 

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Why a 3 core cable, the earth is redundant as you should be using a local earth electrode and 30mA Rcd. Our hosts do not sell 2 core SWA in any sizes larger than 2.5, so I would use a 6mm 4 core and parallel the conductors to give 12mm effective. However, the VD calcs need doing. The welder is a big thing current wise and it will have an inrush current on starting the arc, as will the chop saw and most other tools with a motor. Then of course their is the future, this looks semi industrial, need to think ahead.
 
Refuse to Bend said:
Why does it require an electrode?
Click to expand...
I advise the use of a separate earth electrode and RCD as don't know the supply type, if it is a TNC-S it is considered unwise to use the supplied earth terminal on installations outside the zone protected by the equipotential bonding. This is a safeguard against a broken or discontinuous PEN conductor in the network that may allow the neutral and earth terminal voltage to rise way above true earth potential. Then there's the issue of mixed disconnection times to consider irrespective of the supply arrangement. Personally, I would not use the supplied earth terminal at all, but others may do.
 
Bob Rathbone said:
I advise the use of a separate earth electrode and RCD as don't know the supply type, if it is a TNC-S it is considered unwise to use the supplied earth terminal on installations outside the zone protected by the equipotential bonding. This is a safeguard against a broken or discontinuous PEN conductor in the network that may allow the neutral and earth terminal voltage to rise way above true earth potential. Then there's the issue of mixed disconnection times to consider irrespective of the supply arrangement. Personally, I would not use the supplied earth terminal at all, but others may do.
Click to expand...
Nothing stopping you employing the main installation earth. Whilst people may implement an alternative earthing system there is no requirement under BS7671 to do so.
 
Refuse to Bend said:
Nothing stopping you employing the main installation earth. Whilst people may implement an alternative earthing system there is no requirement under BS7671 to do so.
Click to expand...
BS7671 will refer at some point to disconnection times, don't know the reg number but it will be there. If a common earth source is used for both installations outside and inside the equipotential zone, how is the disconnection time for the external installation met when a fault voltage to earth on the zone protected by bonding (longer disconnection time) appears on the protected metalwork on the installation outside the protected zone for the time permitted inside the protected zone. It cannot comply with the disconnection time for installations outside the bonded zone.
BS 7671 is the MINIMUM standard that we must comply with, it sets out good practice and basic safety, it does not delve deeply into the area of 'special installations' nor is it installation specific. The closest we have with this outside installation in BS 7671 would be a caravan park installation, look at that, understand why the recommendations are made and you will then understand why a separate earthing system is required.
 
Bob Rathbone said:
BS7671 will refer at some point to disconnection times, don't know the reg number but it will be there. If a common earth source is used for both installations outside and inside the equipotential zone, how is the disconnection time for the external installation met when a fault voltage to earth on the zone protected by bonding (longer disconnection time) appears on the protected metalwork on the installation outside the protected zone for the time permitted inside the protected zone. It cannot comply with the disconnection time for installations outside the bonded zone.
BS 7671 is the MINIMUM standard that we must comply with, it sets out good practice and basic safety, it does not delve deeply into the area of 'special installations' nor is it installation specific. The closest we have with this outside installation in BS 7671 would be a caravan park installation, look at that, understand why the recommendations are made and you will then understand why a separate earthing system is required.
Click to expand...
What are equipotential and protected zones?
Separate earthing systems are not required.
 
Refuse to Bend said:
What are equipotential and protected zones?
Separate earthing systems are not required.
Click to expand...
I think he’s referring to the Equipotential location.
He’s asking if there’s been any consideration of whether a prolonged earth fault in the house will liven up the metalwork within the Garage, where there would be a difference in potential to the General Mass of the Earth.
A similar situation to that which can occur with caravans.
 
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