RCD tripped after power out restored

Discussion in 'Electricians' Talk' started by diymostthings, Jul 2, 2017.

  1. diymostthings

    diymostthings Well-Known Member

    Returned home after 5 days away. RCD for downstairs ring main tripped - fridge freezer stuff melted (and stinking). Thought it must just be a nuisance trip but then next door neighbour said the street had had a power outage 4 days ago.

    Question for you lot:

    Can an RCD trip when power is restored after a power outage (e.g. through a spike or surge of some kind)? If so shpuld I complain to/(claim off?)the distributor? (We are PME TN-C-S).

    Thank you.
     
  2. Pollowick

    Pollowick Screwfix Select

    Yes they can. Everything is coming back on line at the same moment. Motors starting, filters and suppressors being energised - lots of little bits of leakage to earth and they all add up. Surprised that it has started to stink already though. A decent freezer should keep the -17c for almost 24 hours and then will take a while to get up to 0 degrees.

    It is a good reason to have a separate fridge/freezer circuit with a dedicated RCBO which means that if something else trips the main RCD the fridge/freezer continues working. Only if it has a problem itself will that one trip.
     
    masterdiy likes this.
  3. masterdiy

    masterdiy Screwfix Select

    I would imagine it would be a household Insurance claim. They don't normally quibble with Freezer claims.
    Be good to let us know how you get on.
    Pollowick, that sounds like a good idea. I'll get my circuit checked out. Just in case.
     
  4. Pollowick

    Pollowick Screwfix Select

    £30 for an RCBO is a small price to pay. Even with the small extra cost of install at new or rewire it will be less than the excess on a claim and give greater peace of mind.
     
    KIAB likes this.
  5. JP.

    JP. Screwfix Select

    Concur - have always run a dedicated to the fridge freezer myself. Nowadays of course it would be via an rcbo unless you wanted to faff with buried depths or galv conduit and stuff etc. Under the 16th and below of course it would be of the non rcd side of the split loader.
     
    KIAB likes this.
  6. KIAB

    KIAB Super Member

    Another one here who has a dedicated feed to the fridge freezer, orginally a MCB protected, now changed to a RCBO.
     
  7. diymostthings

    diymostthings Well-Known Member

    Totally agree. However out CU has RCBO's only for the lights (D/Upstairs)and the cooker. These did not trip. I guess the fridge and boiler (both on the RCD side) are more likely to trip due to the nature of the load but if I transfer the fridge to an RCBO, surely this might still trip?
     
  8. Pollowick

    Pollowick Screwfix Select

    The RCD will be a 30mA - there will be the boiler circuitry and pump, fridge freezer, TV, computers, chargers, and many other devices that have a very small leakage which may peak at switch on. Add them all together and you could go over the 30mA fault current, which can actually be as low as 20mA. The chance of one device alone causing a trip is very unlikely or it would happen on a regular basis. And given your other RCBOs did not trip then it says that there was not a network fault that caused the RCD to trip, just everything coming back-on at the same time.
     
    KIAB likes this.
  9. Bazza

    Bazza Screwfix Select

    Indeed. I guess we have all been to sites where the RCD will not reset, until you turn off all the MCBs, reset the RCD, then turn the MCBs on - one at a time.
     

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