Armour cable suitable

Discussion in 'Electricians' Talk' started by Bigacey, May 25, 2024.

?

Is 10m armoured of sufficient kva

  1. 12

    2 vote(s)
    100.0%
  2. 12

    2 vote(s)
    100.0%
  3. 12

    2 vote(s)
    100.0%
Multiple votes are allowed.
  1. Bigacey

    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
     
  2. Refuse to Bend

    Refuse to Bend Active Member

    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.
     
  3. Bazza

    Bazza Screwfix Select

    ^^^^^what he said!!^^^^^^
     
  4. WH55

    WH55 Screwfix Select

    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 ?
     
  5. Rulland

    Rulland Screwfix Select

    I'd go deeper:cool:
     
  6. spinlondon

    spinlondon Screwfix Select

    I voted for 12, three times.
    Hope that helps.
     
  7. Bigacey

    Bigacey New Member

     
  8. Bigacey

    Bigacey New Member

     

    Attached Files:

  9. Bigacey

    Bigacey New Member

    “L
    electrician is away on holiday I hope to have cable in for his return
     
  10. Bigacey

    Bigacey New Member

    Single phase 250 welder I use for wrought iron work
     
  11. Bob Rathbone

    Bob Rathbone Screwfix Select

    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.
     
  12. Refuse to Bend

    Refuse to Bend Active Member

    Why does it require an electrode?
     
  13. Bob Rathbone

    Bob Rathbone Screwfix Select

    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.
     
    WH55 likes this.
  14. The Happy Builder

    The Happy Builder Screwfix Select

    Anything more than a DIY hobby welder requires a DNO notification ;)
     
  15. Refuse to Bend

    Refuse to Bend Active Member

    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.
     
  16. The Happy Builder

    The Happy Builder Screwfix Select

    I assume that should say the garage has been rewired?

    Is there a dedicated 32 amp circuit and socket for the welder in the garage?
     
  17. Bob Rathbone

    Bob Rathbone Screwfix Select

    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.
     
  18. The Happy Builder

    The Happy Builder Screwfix Select

  19. Refuse to Bend

    Refuse to Bend Active Member

    What are equipotential and protected zones?
    Separate earthing systems are not required.
     
  20. spinlondon

    spinlondon Screwfix Select

    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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