I was supplied with an Intermatic 120-12v transformer. There are no wiring connection diagrams. The transformer has 4 wires( bk, wh, bl and y)on one side and 2 black wires on the other side. How do you connect supply and the pool light to this?

Any other useful info? Number, wattage or VA?

It could be a 12/24 transformer or even a 6/12 V transformer or even a 120/240 primary and a 12 V secondary.

Need a little more info like any numbers or markings on the transformer.

Numbers on transformer/ two black on one side bk,wh,bl,yl on the other side (120/12v 3000va . 9817)I am hooking it up to my AQua Plus automation and chlorination system control panel. Where do the wires go?

Forget right off, but the 4 wires out may be Common, 12 Volts, 13, 14 out.
The 2 Blacks(if they are smaller than the 4 wires)are your 120 Volts in.
A Meter will determine the outputs, a lower voltage may save a little electric and extend bulb life.

The wiring diagram should be on the backside of the front panel, once you take it off. If it isn't, the two black wires are your low voltage connections and would be connected to the two wires coming from your pool light (it doesn't matter which goes on which). The green wire from the pool light would be connected to the ground bar in the transformer box.

On the other side, a 12V installation would mean connecting your 110V line voltage to the black wire, your white neutral to the white, and your ground wire to the same ground bar. The blue and yellow wires would be capped off individually with a wire nut. If you want to wire for 13V or 14V, connect your 110V line voltage to the yellow or blue, respectively, and cap off the black wire and the other unused color.

Pooltek, please check the dates of the posts you are replying to.

Pooltek, I missed it was an Intermatic, you are correct on this.