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16A on Ring

RustyH
Evening all,


I have a client who is looking for their swimming pool heat pump to be wired up. Manual requests for a 16A connection (although client has been running off a 13a plug!!).

The layout of the house and garden restricts the direct connection to the CU to being long and messy. 


The most direct route is to the lower socket ring. Im sure I remember reading on the old forum that a 16a RCD can be classed as a FCU. 

I can not seem to find reference to this in the regs though, is it stated in there?


If it is acceptable I could spur off this lower ring, in to a weatherproof CU with a double pole 16A RCD, then run SWA up the garden to the heat pump. 


Cheers

Rusty

  • 0
    installation instructions are here https://www.bosta.co.uk/all-products/pool-installation-maintenance/heating-systems/heat-pumps/hydro-pro-heat-pump-type-p-on/off-15020 for the P12. they list a few odd things

    1. USE SUPPLY WIRES SUITABLE FOR 75℃

    2. Make sure that there is circuit breaker for the unit, lack of circuit breaker can lead to electrical shock or fire. 

    3.Appx 6.2

    Nameplate maximum current-No more than 10A

    Phase line- 2h1.5mm2

    Earth line- 1.5mm2

    MCB- 20A

    Creepage protector - 30mA less than 0.1 sec

    4.  To complete electrical hookup, connect Heat Pump by electrical conduit, UF cable or other suitable means as specified (as permitted by local electrical authorities) to a dedicated AC power supply branch circuit equipped with the proper circuit breaker, disconnect or time delay fuse protection. 

    Disconnect - A disconnect means (circuit breaker , fused or un-fused switch) should be located within sight of and readily accessible from the unit, This is common practice on commercial and residential air conditioners and heat pumps. It prevents remotely-energizing unattended equipment and permits turning off power at the unit while the unit is being serviced.

    5 An all-pole disconnection device which has at least 3mm clearances in all poleV , DQG have a leakage current that may exceed 10mA, WKH residual current device (RCD) having a rated residual operating current not exceeding 30mA, DQG disconnection must be incorporated in the fixed wiring in accordance with the wiring rules. 

    6 this site https://worldofpools.com/products/hydropro-p12-swimming-pool-heat-pump specifies a type C or D breaker, couldn't find that in the instructions though
  • 0
    OlympusMons:

    installation instructions are here https://www.bosta.co.uk/all-products/pool-installation-maintenance/heating-systems/heat-pumps/hydro-pro-heat-pump-type-p-on/off-15020 for the P12. they list a few odd things

    >

    >


    terms such as "UF cable" (underground feeder ie outdoor suitable), "branch circuit" and "local electrical authority" suggest some American influence there.


  • 0
    A heat pump in a rack is not really a water heater in the normal hot resistance sense though, more of a fridge mechanism with attitude. I also suspect it was not quite what was in the minds of the authors of the OSG, who I think really meant 'only diddly little 1kW handwashers are OK spurred from  a ring anything else needs it's own cable ' but embroiled themselves in the standard writers English, and somehow failed to say so.

    The stored water volume is only really relevant in the sense of how long the element  will be on for when first switched on and cold, a regualtion that made some nod to the element rating might have been better. If you really want to worry about average load and diversity, then the water consumption is more relevant. Some of those diddly hand wash heaters manage nearly 100% utilization in busy works wash rooms and similar at certain times of day.
  • 0
    RustyH:

    So if its running current is 7.8A, and any induction motor surges would probably be short enough in time to not blow a 13a BS1362 fuse, Could this work off a 13a FCU spur?


    I think that you have answered your own question. If it hasn't been blowing a 13 A fuse in a plug, there is no reason why it would do so in an FCU.


    Those instructions look as if they have been translated by rather early software. I know that we are supposed to follow manufacturers' instructions, but when they have been so comprehensively mangled, it seems like an exercise in futility.


  • 0
    Thanks again with all the guidance.


    As mentioned, Im not sure a heat pump fits in the OSG H5 catagory, as it doesnt contain any form of resistive heating element. The heat is produced through thermodynamic compression, so the electrics are only driving motors (and a host of sensors).


    There seem to be mismatch with UK sellers recommending 15A and the instruction 20A. Maybe the 20A is manufacturer overkill so they don't get returns due to tripping of lower rated protection devices during induction motor surge. The client hasnt had to replace the 13A plug fuse.


    The lower socket ring is protected by a double pole 30mA RCD at the CU
  • 0
    RustyH:

    Thanks again with all the guidance.


    As mentioned, Im not sure a heat pump fits in the OSG H5 catagory, as it doesnt contain any form of resistive heating element. The heat is produced through thermodynamic compression, so the electrics are only driving motors (and a host of sensors).


    There seem to be mismatch with UK sellers recommending 15A and the instruction 20A. Maybe the 20A is manufacturer overkill so they don't get returns due to tripping of lower rated protection devices during induction motor surge. The client hasnt had to replace the 13A plug fuse.


    The lower socket ring is protected by a double pole 30mA RCD at the CU


    from what I gather from googling a "branch circuit" https://www.thespruce.com/what-are-branch-circuits-1152751 it doesn't mean a spur from a socket circuit, it means its own dedicated final circuit from the CU. Ignore MIs, even crappy ones, at your peril.


  • 0
    No we don't have to follow manufacturers instructions. We have to take account of them. They are often wrong anyway.
  • 0
    I have assumed the original poster is the same RustyH as on the old forum.


    We had a Discussion  started by RustH four years ago about matters relating to socket ring circuits, it didn’t actually go into the issues of supplying ornamental pond equipment, which this one already is or supplying swimming pool equipment as is proposed.


    A discussion forum is not the place to redesign this socket circuit, it needs someone onsite to decide what needs to be done. Raising questions about technical issues on a forum is one thing, trying to do the complete design is another.


     Andy Betteridge
  • 0
    Sparkingchip:

    I have assumed the original poster is the same RustyH as on the old forum.


    We had a Discussion  started by RustH four years ago about matters relating to socket ring circuits, it didn’t actually go into the issues of supplying ornamental pond equipment, which this one already is or supplying swimming pool equipment as is proposed.


    A discussion forum is not the place to redesign this socket circuit, it needs someone onsite to decide what needs to be done. Raising questions about technical issues on a forum is one thing, trying to do the complete design is another.


     Andy Betteridge 




    Hi Andy,


    Correct, I used to use the old forum during my training and had some fantastic help from a number of members that are still active on this forum, which is great to see. 


    The questions back then where indeed regarding ring circuits, questions I had during my training. 


    This question was merely to seek some guidance on what I had read on this forum previously to do with adding a 16A RCD / MCB on a ring.


    Surely a forum is a place to allow those who may not have gained years and years of experience yet to ask questions they have uncertainty of, and get guidance from those that may have been in that situation before. 

    It also allows those questions to be in the domain for others that might be unsure at the time of assessing a job to research the answers on the forum. 


    I don’t feel I have asked for anyone to design me the circuit, I have thrown up what I think would be right and guidance has been shared. 


    If you feel the questions I have asked are not to the protocol the forum is trying to promote that please could you get a member of the admin team contact me to advise what is acceptable and not acceptable in this forum. 


    Much appreciated 

     


  • 0
    Here is what you are looking for,  but for what you are proposing seems totally inappropriate. 


    080ca975a5f92cb84f5817aca89c2296-original-20200625_091036.jpg

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