I'm trying to add in a bell transformer to my existing Hager consumer unit. It's from about 1995. I live in England. The first image below shows the front cover, with five spare ways and their covers. So far so good.

Fron cover

But the next image shows the existing MCBs that are fitted. You can see that there is a gap between them. You can also see that there is no traditional metal DIN rail. This is something a bit like it made of plastic that I'm going to call the DIN plate. It's screwed into the same position that the DIN rail would have gone. However, you will see from this image and the subsequent one that the DIN plate is in fact Tee shaped. It is not a purely horizontal rail. There is a vertical leg in the middle of it. This leg fills the gap between the existing MCBs either side.

Existing MCBs DIN plate detail

You can see therefore that there is no way to attach other items to the middle section of the DIN plate. The consumer unit is effectively full, even though there is a gap and provision for other items in the cover. You can also see that the bus bars allow for other items.

The final image is a smaller Hager unit next to this one, also featuring such a DIN plate. It too has spare terminals along the bus bar, and removable covers in the enclosure.

Another example

I've talked to an electrical supplier, and he's never heard of such a thing. I've looked on Google Images for a 12 way (6 + 6) Hager consumer unit, and they all have the traditional metal top hat DIN rail. There is not a single similar consumer unit anywhere on Google.

Why do I have something that Google doesn't? And more importantly, how can I fit my bell transformer?

  • In the US, we'd just wire the bell transformer at a junction box.
    – keshlam
    Commented Oct 3, 2015 at 1:16
  • And to extend what @keshlam has said, many US deployed bell transformers are mounted onto an electrical box cover plate with the mains side wires extending through the cover and directly into the box. The low voltage terminals are on the transformer case external to the electrical box such that the low voltage wiring does not intermingle with the mains wiring connections. Since pictures are worth many words here is a typical setup. farm8.staticflickr.com/7704/16516219764_e24d698f2e_o.jpg
    – Michael Karas
    Commented Oct 3, 2015 at 13:32
  • Have you tried removing one of the existing MCBs to look behind it?
    – longneck
    Commented Oct 3, 2015 at 15:25
  • @longneck I have now. It just hangs off the top of the DIN plate. There are no other attachments, and is stopped from wobbling by the copper bus bar at the bottom. Seems very cheap and shoddy.
    – Paul Uszak
    Commented Oct 4, 2015 at 21:50


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