3 Pin vs 7 Pin Photocell

Today we are going to compare the differences among 5 pin vs 3 pin vs 7 pin photocell, and show you their wiring diagram, so you would know which one you should to take for your application.

NEMA is abbreviation of “National Electrical Manufacturers Association”, which is an ANSI-accredited Standards Developing Organization made up of industry leader, engineer, electrical experts, technicians and scientists.

Therefore, a NEMA street light socket refers to the standard socket patterns that is quite common in United States.

First, let’s take a look at one picture to tell the difference betwen the 3 pin photocell, 5 pin photocell and 7 pin photocell, you will get a quick undersanding by its appearance.

1. What’s 3 pin photocell ?

3 pin photocell has 3 prong outside that can be inserted into the three NEMA socket’s slots(picture 1 above),  where hot wire, neutral wire and ground wire comes from the fixture.

• “L”- hot cable: black wire
• “N” – neutral cable: red wire
• “G” – ground cable: white wire

When you twist lock 3-pin photocell onto the 3 pin photocell receptacle, the light is connected completely. It can detect the brightness to automatically control on/off based on its default factory setting.

3 pins photocell sensor is quite commonly used for LED lighting dusk to dawn control, because it saves more energy than non-photocell version, and more convenient for automatic operation without people’s additional attention to switch it on/off.

2. What is 5 pin photocell ?

5 pin photocell has 3 prong as well, but has two extra copper contact, as you can see clearly from picture 2 above, there are also two corresponding contact pads on the 5 pin photocell receptacle, where at its reverse side the dimming wire(dim+ wire & dim- wire) is added.

• “L” – hot cable: black
• “N” – neutral cable: red wire
• “G” – ground cable: white wire
• “dim+” – dim hot wire: green wire
• “dim-” – dim neutral wire: blue wire

If  your street light or parking lot light has 0-10V or 1-10V dimmable driver, where there is  dimming output wire come out, then with the 5 pins photocell,  you can have more complicated light control than 3 pin photocell.

3. What is 7 pin photocell ?

7 pin NEMA photocell sensor also have 3 long prong but has 4 copper dimming contacts from picture 3 above.  It supports more dimming/ two signal channels protocols at a time. e.g. low voltage 1-10vdc signal and DALI dimming / motion sensing input signal etc.

As we can see from the 7 pin photocell socket, it has 7 wires coming out.

• “L” – hot cable: black wire
• “N” – neutral cable: red wire
• “G” – ground cable: white wire
• “dim+” – dimming hot cable: violet wire
• “dim-” – dimming neutral cable: gray wire
• additional control cable 1: Orange wire
• additional control cable 2:Brown wire

The 2 additional control wires should be capped off or insulated if you don’t use it.