# 230V AC to 24V AC Transformer Wiring (Black, Red, Brown, Brown)

I'm setting an irrigation controller and I need a 24V AC source to switch the irrigation solenoids.

Since I have 220V AC, I asked the electrical store for a 220VAC to 24VAC transformer and they gave me this one, but I'm unsure how to wire it. Which wires should connect to live and neutral on the 220VAC supply and which are live and neutral on the 24V output? My best guess is that the black wire is used on both the input and output as a common neutral, but don't want to chance it.

The below sticker came with the transformer:

The transformer has 4 cables, one black, one red and two brown:

Any advice appreciated!

• Just as it says on the label. 0 = Black = Neutral, 230 = Red = Live. The two brown ones connect to the AC output in any order. DO NOT connect Neutral to the secondary, but you can GROUND one leg of the AC output (and probably should, since the transformer doesn't appear to be double insulated)
– user16324
Commented Jan 30, 2021 at 15:13
• @BrianDrummond are you referrnig to grounding of the secondary? As follows ucarecdn.com/1a09bc3f-2dbb-4f54-9b99-cbe709206a40/-/preview ? Commented Jan 30, 2021 at 15:29
• Before you do it, ask yourself is it legal and safe for you to do mains electrical work in a manner that the result is not dangerous, i.e. nobody dies because of electric shock or the device does not burn a house down if something goes wrong. Commented Jan 30, 2021 at 15:51
• @MatthysDuToit Yes like that.
– user16324
Commented Jan 30, 2021 at 16:33

## 1 Answer

Which wires should connect to live and neutral on the 220VAC supply and which are live and neutral on the 24V output?

• Black and red are 230 volts
• Brown and brown are 24 volts

My best guess is that the black wire is used on both the input and output as a common neutral

No, the two transformer windings are isolated from each other.

Since I have 220V AC, I asked the electrical store for a 220VAC to 24VAC transformer

Well, nearly right - they shop supplied you with a 230 volts AC rated transformer so, on a supply of 220 volts, you can expect the 24 volts AC output to be around 23 volts RMS.

• Thanks, so the two browns are live and neutral (interchangeable) on the 24V output? Commented Jan 30, 2021 at 15:15
• No, they are not called live and neutral on the isolated output winding. The terms live and neutral are reserved for the incoming voltages from your distribution/fuse box. Call them 24VAC_1 and 24VAC_2 if you want to give them a name. Commented Jan 30, 2021 at 15:17
• Makes sense, thanks for assisting! Commented Jan 30, 2021 at 15:20