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Unusual MCB

Sparkymania
Here's an interesting one.

Federal Electric 20A MCB. Had no type on it and was taking a long time to trip. Opened one up and discovered why it didn't have a type.

Others with it were ECC but virtually the same design. Only thermal. Both are plug in types called stab-lok and are bakerlite.


No instantaneous trip mechanism. Only a thermal one.



34200b5e07a12e120f5fc679b8b1b9aa-huge-mcb-with-no-instantanious-trip-mechanism-4.jpg
  • 0
    This page, paceforensic, has some old studies of US breakers.  See e.g. the Publication 3 on the right (.. the myth of safety). It suggests some have a magnetic trip, but that this is at a high level compared to typical European MCBs of B or C type.  The first of the videos also points out how a low magnetic trip is useful against arcing in cables.  I hadn't seen a purely thermal US MCB before, for main panels ('CU') rather than just inside appliances and starters (I associate stablok with panels, but it's probably more general). Interesting...
  • 0
    Sparkymania:

    Looking at the others on ebay I thought the colour may have some significance too as they have a label on the front stating the type so I would say they do have a magnetic mechanism.

    However, some of the black toggled ones also have a type stated on the front as well so I would say the coloured ones are all later ones and they started making them with magnetic mechanisms first with the black toggles before colouring them.


    I still couldn't find an RCBO with a type stated on the front or on the sides (from the ones with side pics) so that still begs the question as to whether these RCBOs have a magnetic mechanism.

     


    As far as I can see, the ones with the green toggles are type 2, the orange ones type 3, and the black ones type 4. If there is no type written on the device, it seems reasonable to assume that they have no magnetic trip mechanism.


  • 0
    A good steer from Chris.


    They are BS 3871 MCBs.

    White handles are Type 1.

    Green handles are Type 2.

    Orange handles are Type 3.

    Black handles are Type 4.


    They are known to be problematic. Just putting you finger tip on a single breaker will reveal a lot of wobbeling around between the MCB and the bus bar. I have see a few occasions where there has been a flash over on the bus bar which has caused upstream protection to operate. On one occasion it took out 2 services fuses. 


    If I see them I recommend a board change.


  • 0
    John Peckham:

    If I see them I recommend a board change.


    Well I was going to invite you round, but in that case ...


    Mine all have orange dollies.


  • 0
    Chris


    That is a shame as I was looking forward to afternoon tea with scones, strawberry jam and clotted cream round at yours!
  • 0
    John Peckham:

    Chris


    That is a shame as I was looking forward to afternoon tea with scones, strawberry jam and clotted cream round at yours!


    JP, it was the OP who mentioned "Bakerlite", Chris only has orange lollies.


  • 0
    I thought he said "doily" like the ones that go under the scones?
  • 0
    I've found an RCBO on ebay for a tenner. Don't know how long it will take to get to me as the postal service has massive delays at the moment.

    As soon as I get it I will open it and put the pic of it on here.


    Should be interesting to see if a company would make and RCBO with no magnetic mechanism. There was no excuse to make the MCBs that are used in DBs without them, Even worse if they made RCBOs without them.

    From the info about FE's failures and falsifying their testing they deserved to go out of business.


    From now on I will fail any of their DBs with a code 2 and include the pics of the insides of the MCBs and RCBOs and the 2 reports on them.

    Even the ones that have magnetic mechanisms in as the reports says they are prone to jamming, even the single pole ones.

    The reports seem to focus on the bakerlite ones. Not too sure about the newer plastic 60898 ones. They must have gone out of business just after manufacturing those.

  • 0
    Chris Pearson:
    John Peckham:

    If I see them I recommend a board change.


    Well I was going to invite you round, but in that case ...


    Mine all have orange dollies.




    Thinking further about this, I wish that they didn't because the Zs on some socket circuits (e.g. to my workshop at the far end of the house) is just over the limit.


    Why fit type 3 MCBs in a dwelling? ?


  • 0
    Chris Pearson

    Thinking further about this, I wish that they didn't because the Zs on some socket circuits (e.g. to my workshop at the far end of the house) is just over the limit.




    possibly a victim of the introduction of Cmin?


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