installation · 4 min read

Powering Masterclock clocks: 230 V, 24 V or PoE

Some clocks plug straight into a wall socket, others do not. What is supplied, when is PoE the better choice, and what do you need to prepare yourself?

Choose your reading level

A clock needs power, just like a lamp. Big clocks have a plug that goes straight into the wall socket. Small clocks are too small for such a plug: they come with a little black box, and that box turns the 230 volts from the socket into the 24 volts the clock needs. That box has to hang somewhere. Or you use the network cable, because it can carry power as well.

When ordering a clock, this is the question that most often goes wrong: how does power reach the unit? The answer differs per model, and the manufacturer uses a term that is easily misread.

The confusion: “24 V DC plug” means an adapter

Masterclock refers to a *24 V DC plug*. That sounds as if you have to supply 24 volts yourself. You do not. It is a power adapter: you plug it into an ordinary wall socket and it converts that into the 24 volts DC the clock needs.

The adapter: 100-240 VAC in, 24 V / 1.0 A out, 2.1 mm barrel jack, with interchangeable plug heads for EU, UK, US and AU-NZ. It is supplied as standard with the models that need it.

Three situations

1. Clock with a normal mains inlet. The larger displays have a built-in mains inlet. You connect an ordinary power cord, and that cord is supplied with the plug type for your country. Nothing else to prepare. 2. Clock with a small mains inlet. On some models the inlet is smaller: the cloverleaf plug (IEC 60320-C5) or the figure-8 plug (C7). Still plain 230 volts; only the shape of the cord differs. 3. Clock without a mains inlet. On the smallest clocks there is physically no room for a mains inlet. They run on 9 to 28 volts DC through a 2.1 mm barrel jack, and ship with the adapter.

What to prepare for situation 3

This is the point that costs time on site. The adapter has to sit somewhere: in the false ceiling, behind the wall, or in a nearby cabinet. Allow for that position at design stage. Discovering it on installation day means standing still.

Two alternatives: supply your own 24 V DC at the clock position, or use PoE.

When PoE is the better choice

With PoE, data and power run over the same network cable. Only one cable runs to the clock.

Already have a PoE switch? Then PoE is the simplest choice, at no extra cost.
No room for the adapter at the clock? Then PoE is the better installation solution, even if you have to buy an injector for it. The injector sits in the technical room, where there is room.
Room for the adapter and no PoE switch? Then PoE is an unnecessary cost, because the adapter comes as standard.

Note: not every model has PoE. The NTD200, TCD200 and TCDS24 run on DC only.

Which models have no mains inlet

Model	DC input	PoE
NTDS24, NTDS24-DF, NTDS24-8AL	12-24 VDC	yes
NTDS26, NTDS26-8AL	24 VDC (optional C8 inlet)	yes
NTDS1616	12-28 VDC	yes
CLDNTD12, CLDRNTD12, CLDTCD12	24 VDC	yes
NTD200, TCD200, TCDS24	9-28 VDC	no
RC600	9-28 VDC	yes

All of these have a 2.1 mm barrel jack and ship with the adapter.

Not sure about your model?

Ask us before you install. A badly prepared power supply is the cheapest mistake to avoid and the most expensive to fix afterwards.

From theory to practice: browse the NTP digital clocks in the Masterclock range from Daylight.

The supplied adapter is an XP Power VER24US240-JA: 100-240 VAC in, 24 V / 1.0 A out, 2.1 mm barrel jack, with interchangeable EU/UK/US/AU-NZ heads. The DC input accepts a range (12-24, 12-28 or 9-28 VDC depending on the model), so an existing 24 V installation can be used directly. PoE is 802.3af (max 12.95 W at the device); without a PoE switch, the PSPOE15 delivers 48 VDC / 15 W on a single port. The NTDS26 and NTDS26-8AL can optionally be fitted with a C8 mains inlet; the other twelve DC models cannot.