In a Pickle With Replacing Integral Transformer

[Member]

Replacing a transformer in a ceiling fitting but the new transformer has terminal blocks either side whereas the old transformer had all terminal blocks together. How do I know which wire should go to which terminal? (Black is old one, White is new)

@PigletJohn or anyone else who knows electrics

You have to carefully read all the text on the two devices, and wire into the terminals that say the same thing. I can't quite read them. Maybe if you take a bigger pic of each of them, the right way up, it will be possible. I can probably understand the German one, if I can read it.

You do have 12v Halogen lamps, don't you? Not LED?

I think I can see wires coming out of one of them like a spider's legs. With this type you have to have the same length wire going to each lamp so the voltage drop is the same, otherwise some will be dimmer than others, and they may have a special connector.

BTW if you have any more of these, I think it will be less trouble, in the long run, to change over to mains-voltage LEDs.

Yes they are 12v halogen taking G4 capsules

Photo of original transformer - think I’ve been a dufus 🙄

So "primary" is mains input, marked 230v, and "secondary" is the safe extra-low voltage of (about) 12volt. The Primary L wire should be insulated in brown (or red, if old) and the N should be blue (or black, if old). The earthwire, if present, will be green and yellow (or green, if very old).

It looks like the incoming flex for the Primary supply is gripped by that cable gland in the middle of the "Eaglerise" one. The nut tightens to grip it.

On the black one, that might be a black cover with cord grips under it. The flex sheaths should be gripped by something to prevent them being able to pull out of the terminals. If necessary, those white plastic pillars can be used for a strap-type cord grip to be screwed in. They ought to have been supplied, if they are needed. I don't know where you'd buy such a thing, it's one of the things you accumulate in your electrical toolbox, when you take them off old devices or plugs. Maybe if you need them but haven't got them, you could email the maker or vendor and they might send you a couple.

If you have to connect any wires outside the transformer, they must be in an insulated enclosure like a choc-box, I can give you a link if you want.

You are a joy, John. Thanks for all your posts.

I’ve done it, thanks for the replies @PigletJohn