Making use of Outdoor Isolator Switch

Discussion in 'Electricians' Talk' started by Vince82, May 11, 2022.

  1. Vince82

    Vince82 New Member

    Just a little advice and clarification please.

    Property purchased and there is 4mm cable fed from a 32A breaker in the DB which runs to an isolator switch outside. From this I am guessing that the previous owners had this installed for a hot-tub

    My requirement would be to install a 2 gang outlet socket approx 40m away with 2.5mm outdoor cable in conduit that would run along the fence to avoid any unnecessary digging with SWA.

    With the 32A breaker and 4mm from the DB is it permitted to connect 2.5mm to this at the isolator switch?
     
  2. jonathanc

    jonathanc Guest

  3. Ind spark

    Ind spark Screwfix Select

    Swap the isolator for an ip rated spur, or put one next to it.
     
  4. Vince82

    Vince82 New Member

    Thanks Ind Spark

    From IP rated Spur 4mm can be run to outdoor socket to compensate for any volts drop
     
  5. Bazza

    Bazza Screwfix Select

    No, because 2.5mm cable is not big enough for thd potential current of 32amp.
    The simple solution is to run 4mm cable from the isolator switch.
     
  6. The Happy Builder

    The Happy Builder Screwfix Select

    The answer is probably to change the 32 amp MCB for a 16 amp MCB, but that needs confirming.
     
  7. Ind spark

    Ind spark Screwfix Select

    That is simple, I wrongly assumed he already had the 2.5mm.
     
  8. Vince82

    Vince82 New Member

    Thanks Bazza

    That dawned on me after I posted ‍♂️

    Keeps things simple and straightforward with a 50m cable run fed from a 32A breaker on 4mm cable to the outlet socket
     
  9. The Happy Builder

    The Happy Builder Screwfix Select

    If you only ever want one double socket that may be over the top.
     
  10. CeSparky1

    CeSparky1 Active Member

    You probably want to make sure if its not already that it is RCD protected..

    There are a few things you have to consider here, the current carrying capacity of the cable (2.5mm will not be sufficient for 32A)
    Voltage drop - not done the calculations, but even if you lower the rating of the OCPD you may need to still increase the size of the cable to compensate.
    And then there is the type of cable and how it is fixed, Just using outdoor cable run along a fence is not really suitable, the cable can easily be damaged, SWA would but much more suitable, correctly glanded and earthed, clipping it to fence panels is not really great, as if it falls down it can damage the cable, and is the fence actually yours? The neighbour could try to remove the fencing to replace and not see there is a cable your side (Another reason for SWA)..

    I really think you should contact an electrician as you want it to be safe, I am guessing your reasoning to avoid SWA is mainly because you don't know how to gland it? Get and electrician in but work with them, it doesnt take a rocket scientist to clip up a cable or dig a trench etc, you can still do the donkey work, but let the sparky do the design and connections and importantly something you have not considered is testing... Do you know how to properly test a circuit and do you have the required test equipment?
     
  11. sparky steve

    sparky steve Screwfix Select

    Surface fixed cables may be fixed to permanent structures, however i would not recommend cliping to timber fencing because of the following reasons..

    Wood preservatives may attack the cable sheath.

    Timber fencing is unlikely to be sufficiently rigid.

    The life of timber fencing is likely to be less than that of the cable.

    Damage sustained by the fence due to high winds could possibly result in the cable being damaged and introduce the risk of electric shock.
     

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