How To Read the IEC 60309 Clock

IEC 60309 Clock

If you’ve ever tried to buy a IEC 60309 pin and sleeve wiring device, you’ve undoubtedly seen this clock before…


IEC 60309 Clock

What does this mean? How should it be interpreted? Is this for the male or the female? All of these questions will be answered in the next few paragraphs.

Step 1: Wires

As you can see, there are three circles within the clock. These represent the number of wires that your device requires. You’ll always need at least 3 wires (hot, neutral, and ground) when dealing with IEC 60309 products. In the typical North American market, you will not exceed 5 wires (3 hot, one neutral, and one ground). It’s worth noting that 3 wire devices cannot carry 3 phase power because you need at least 3 pins to carry current. So, by now we should know what level of the circle we need to look in the IEC 60309 clock.

Step 2: Voltage

Next, you need to select the appropriate voltage for your application. In most industrial electrical cases with IEC 60309, you are dealing with AC power and three phase power. Thus, you are likely looking on the outer two rims. Now, simply find the appropriate voltage you require. This should get to you the correct clocking position of the female. We will explain why this matters later. Before we do that, we need to clarify two things about what the clock position actually means:

  1. The clock position relates to the location of the grounding pin (i.e. the biggest pin)
  2. The clock position only matters when the keyway is facing down. The keyway is the protruding section of the circular housing. You can see it’s facing down in this picture

IEC 60309 keyway

Why You Need Both Steps

It may seem obvious, but ignoring one of these steps could result in ordering the wrong product. For example, 250V AC can be in either the 6 o’ clock position or the 9 o’ clock position depending on the number of wires. You need to consider both to be able to effectively read the IEC 60309 clock.

Wait, What About the Female?

We mentioned that the clock represents the female grounding position. Why does this matter? Because if you look at the grounding position of the male, it will not always be the same! Think about it this way: if you put an “L” on your forehead, it will look one way to you and the exact opposite to the person looking at you. Its the same with the clocking for IEC 60309. If you have a male device with no label on it, find the ground pin and then translate it to the clocking position where the female would accept it.

Most Common Configurations

In an industrial setting in the US, the most common settings are 4 wire, 480V and 4 wire, 250V. In Canada, the standard is usually 600V which is in the 5 o’ clock position for both 4 and 5 wire. There are also certain industries where a specific configuration is used such as dual rated devices for data center or refrigeration. If you’re unsure of any of this, consult an expert who should lead you in the right direction.

Summing It Up

The IEC 60309 clock can be daunting but easily conquered by following our simple guide. Make sure you check the number of wires and voltage to get the female grounding position. If you don’t have the female or the label, remember the “L” principle to figure out the clocking position. Good luck!