Retains Dimming Control

[Lewis Hoff]

What do you mean when you say your power taps retain dimming control?

[Anselm]

The power tap is installed between the luminaire and the photocontrol as shown here. It allows for power to passthrough to the photocontrol device on top of it so as to switch the light on/off.

However, some units have 2 or 4 additional contacts added so as to allow for dimming control of the lights. The dimming signals control the power fed to the lamp thereby varying the brightness appropriately to save on power. There are a number of dimming protocols to achieve this like DALI, DMX, 0 - 10V, DSI etc.

More info can be gathered from this blog.

[Obsidian]

What is the difference between the tap with 5 pins (3 contacts and 2 dimming) and 7 pins (3 contacts and 4 dimming)? As in why would i need 4 dimming contacts instead of 2? Also can you provide me with a reference on the dimming protocols here?

[Anselm]

Under the ANSI C136.41 standard there are several dimming control methods. Some like the older 0-10VDC/ 1-10VDC (single channel protocol) method require two dimming contacts to supply the control voltage while others like the newer Digital Addressable Lighting Interface (DALI- 2 channel protocol) require 4 contacts for full functionality. For DALI two contacts pass the voltage to the ballast while the other two relay the control signal.

DALI has more advantages over 0-10VDC dimming such as:

• Being digital it can dim lights to a much precise level
• The 4 contacts allow for two way communication between ballast and luminaire allowing for feedback to the controller
• Appropriate for instances when luminaires need to respond to more than one input device (sensor and manual switch)
• Can accommodate up to 64 ballasts compared to 0-10VDC doing 10

These protocols are defined by the ANSI C136.41 available in the link.