Storage heater control switch problems - questions.

Discussion in 'Electrics UK' started by dishman, 8 May 2021.

  1. dishman

    dishman

    Joined:
    8 Jul 2008
    Messages:
    1,231
    Thanks Received:
    92
    Location:
    Derbyshire
    Country:
    United Kingdom
    A few questions.

    I have a flat with 3, 3.5kw storage heaters. They are wired to their own board, each on it's own circuit.

    At some point in the past, someone installed a 13a fused spur on one of them.

    That switch seems to have completely gone after being in there for a few years. The switch is all spongy and the fuse does not seem to want to pop out, as if it is melted in.

    So,

    1) It seems to me that a 13a fused spur should not have been used in this scenario. Am I correct? Having just had an ECIR, should this have been picked up? I assume that the loads put on the switch rated at 13a was probably slowly degrading the internals. The final straw may have been the input being turned up to high for the first time in a while.

    2) The other two are on what seem to be 20A switches with a neon light. These have had their own issues in the past, hence one being replaced at some point.

    We have been noticing issues with the neon light flickering and going out on some. I know that this may not mean the storage heater is not getting power, but it does seem to have issues getting a full charge sometimes (if charging at all).

    Could the loads over time have started to cause these 20amp switches to fail too? They have been in for about 10 years. Not sure about the brand. Probably B&Q or something. So could a cheap 20A switch fail in this way? Slowly becoming unreliable?

    I checked the connections and nothing was loose. No signs of poor connections, burn marks etc etc. So wondered if it was just a common wear and tear issue with the loads being placed on them for 7hrs every night?

    Finally a technical question, regarding the difference between 20a switch vs a 13a fused spur. Other than the fuse, is it normally about the size, beefiness of the internals? The 20a being able to handle the higher loads?

    Any suggestions on a quality brand as I intend to replace them all for good quality 20A DP switches.

    Thank you.
     
  2. Sponsored Links
  3. AndyPRK

    AndyPRK

    Joined:
    4 Jan 2009
    Messages:
    5,935
    Thanks Received:
    596
    Location:
    Herefordshire
    Country:
    United Kingdom
    Yeah fit 2 new 20A switches.

    MK brand or Crabtree
     
  4. crystal ball

    crystal ball

    Joined:
    28 Apr 2004
    Messages:
    5,527
    Thanks Received:
    340
    Country:
    United Kingdom
    Or Hager
     
  5. JohnW2

    JohnW2

    Joined:
    28 Jan 2011
    Messages:
    49,168
    Thanks Received:
    3,244
    Location:
    Buckinghamshire
    Country:
    United Kingdom
    The neons usually 'fail' (or, at least, start flickering or otherwise become iffy) long before anything happens to the switch - and that is of no consequence.
    If, as I suspect may well be the case, these switches are rarely switched on/off, they would usually last for a very long time.
    Yes, just a beefier switch, designed for 20A rather than 13A.

    Kind Regards, John
     
    • Thanks Thanks x 1
  6. dishman

    dishman

    Joined:
    8 Jul 2008
    Messages:
    1,231
    Thanks Received:
    92
    Location:
    Derbyshire
    Country:
    United Kingdom
    Thanks @JohnW2 and @AndyPRK.

    I too assumed it was just the neons going, but the storage heater does seem to have intermittent charge issues, potentially coinciding with the neon going out, it is very strange.

    I may just replace to see. Given there is no fuse present on those spurs, just a switch and a neon, is this likely to mean they are 20A switches. I have not disconnected them completely to see any ratings that may be embossed inside.

    Regarding one with a fused spur. I assume given the rating of the storage heater, it was the incorrect choice to use one. Should it have been flagged up on an EICR? I'm actually surprised it lasted this long.

    Thanks again.
     
  7. JohnW2

    JohnW2

    Joined:
    28 Jan 2011
    Messages:
    49,168
    Thanks Received:
    3,244
    Location:
    Buckinghamshire
    Country:
    United Kingdom
    Well, if there were an intermittent loss of electricity (due to any problem with the switch or the circuit's wiring etc.) as a reason for the intermittent heating problem, then the neon would go out (when there was no electricity), even if there were nothing wrong with the neon.
    Yes. In fact, I think you'd probably struggle to find any such switch which was not at least 20A.
    Yes, marginally incorrect. The 3.5kW very probably relates to 2409V, so at 230V (which is what we use for calculations) the current drawn would be fractionally below 14A - so, yes, more than 13A, but not a lot more.
    Yes, probably. A fuse (or 'breaker') is meant to have a rating at least as high as the circuit's load ("design current").
    You might be surprised by how long things sometimes last when pushed beyond their design limits :)

    Kind Regards, John
     
  8. ericmark

    ericmark

    Joined:
    27 Jan 2008
    Messages:
    18,916
    Thanks Received:
    1,778
    Location:
    Llanfair Caereinion, Nr Welshpool
    Country:
    United Kingdom
    In an ideal world each storage heater will be supplied from a separate circuit and fuse/MCB, but this is not always the case, the SCHEDULE OF TEST RESULTS will show fuse/MCB size, but not number of outlets from the circuit, so can't really say if a FCU is needed or not as no idea what is supplied from that circuit.
     
  9. dishman

    dishman

    Joined:
    8 Jul 2008
    Messages:
    1,231
    Thanks Received:
    92
    Location:
    Derbyshire
    Country:
    United Kingdom
    I can confirm that each storage heater has it's own 16A breaker in a separate E7 consumer unit.
     
  10. Sponsored Links
  11. ericmark

    ericmark

    Joined:
    27 Jan 2008
    Messages:
    18,916
    Thanks Received:
    1,778
    Location:
    Llanfair Caereinion, Nr Welshpool
    Country:
    United Kingdom
    Then no reason to have a FCU, just some thing else to go wrong, only needs a switch.
     
  12. JohnW2

    JohnW2

    Joined:
    28 Jan 2011
    Messages:
    49,168
    Thanks Received:
    3,244
    Location:
    Buckinghamshire
    Country:
    United Kingdom
    I thought we had already agreed that, quite apart from there being "no reason", it would actually be inappropriate to feed a 3.5 kW load through a (13A) FCU?

    Kind Regards, john
     
  13. ericmark

    ericmark

    Joined:
    27 Jan 2008
    Messages:
    18,916
    Thanks Received:
    1,778
    Location:
    Llanfair Caereinion, Nr Welshpool
    Country:
    United Kingdom
    Yes your right, what I was being careful of is others reading part of the thread, we answer in respect of the posters question, but have to remember google will find posts on forums and then readers may only read part of the answers.
     
  14. dishman

    dishman

    Joined:
    8 Jul 2008
    Messages:
    1,231
    Thanks Received:
    92
    Location:
    Derbyshire
    Country:
    United Kingdom
    An update:

    I swapped out the busted and incorrectly specified fused spur. It is a LAP brand.

    At first glance it looks fine.
    switch-9206.JPG switch-9207.JPG

    but the clue it really had popped badly is highlighted by the fact the fuse carrier won't open, even when prying with a beefy screwdriver , so ignore the damage to the fuse tray, that is due to me trying to pry it out (without success).

    Looking more closely at the back of the fuse carrier you can see signs of melting.
    switch-9208-2.JPG switch-9210.JPG switch-9210-2.JPG

    The next switch was the one with the dodgy neon, but also showed signs of not charging when the neon was not lit. So I decided it was a good practice to replace it too.

    What I found was perhaps a bit more concerning. It was a volex branded 20A DP switch.

    switch-9211.JPG

    No sign of issue on the front.

    switch-9212.JPG switch-9213.JPG switch-9214.JPG

    The back was a different matter.

    note: I had to crack off a bit of the plastic surround as the terminal screw had shifted position so much. This was not broken prior, just melted and probably more brittle.

    Could this have been caused by a connection that was not tight? Or could there be an further issue.

    The inputs were horribly located in this switch so I can imagine they may not have been done up tightly.

    The third storage heater switch was also a Volex 20A DP and showed no signs of issues, but I swapped it out just to be sure.

    All were replaced with Crabtree 20A DP switches. They seemed good quality and had a cable entry retainer which was nice.

    My final question is whether any of this should have been picked up on an EICR last month. The flat was empty (no obstacles) and there are only a dozen or so sockets to check in the flat in total.

    Are there any further checks I should make?
     
    Last edited: 10 May 2021
  15. flameport

    flameport

    Joined:
    10 Mar 2007
    Messages:
    10,101
    Thanks Received:
    2,037
    Location:
    Poole, Dorset
    Country:
    United Kingdom
    If they were in that state at the time of the inspection, they should have been identified and listed on the report.

    Loose connections is the most likely reason, followed by 13A fuses are not intended for use with storage heaters or other large loads that are on for hours at a time..
     
    • Thanks Thanks x 1
  16. sparkwright

    sparkwright

    Joined:
    20 Aug 2009
    Messages:
    8,959
    Thanks Received:
    1,128
    Location:
    Dorset
    Country:
    United Kingdom
    Part of the reason these things failed may have been because the connections were not tightened or terminated properly.

    But you definitely needed something rated at 20 amp.

    This should have been picked up on the EICR in my opinion - an experienced electrician can often tell the wattage of a storage heater just by seeing it, so should have had some doubts when he saw the 13 amp FCU.

    Some testing is limited because there wouldn't be any power to the storage heater supply during working hours, usually.
     
    • Thanks Thanks x 1
  17. dishman

    dishman

    Joined:
    8 Jul 2008
    Messages:
    1,231
    Thanks Received:
    92
    Location:
    Derbyshire
    Country:
    United Kingdom
    Thank you for the replies.

    I am assuming a visual inspection is the only real way to find an indication of a loose connection? There is no circuit test that would identify such a fault?

    In addition, would the fact the storage heaters are high load appliances make them a priority to make such a check during an EICR, not to mention the fact that with one having the wrong switch, it may make an electrician consider checking the others to be sure as @sparkwright suggests.
     
    Last edited: 10 May 2021
Loading...

Share This Page