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How to size the cam lock and latch you need

clock 2.5 minutes | 21 Oct 2019

Someone inspecting cam lock latches on a table

The cam lock latch is often an important cabinet latch hardware requirement. While many enclosures are secured by simple tab style latches, those where access is regularly needed use cam locks and latches.

Some of the applications for cam locks are:

  • Data rack enclosure cabinets
  • A data centre server cabinet
  • An outdoor telecom equipment cabinet
  • An outdoor utility cabinet
  • Outdoor weatherproof electrical enclosures
  • Electrical cable enclosures on industrial machinery
  • HVAC system components enclosures

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Cabinet latch hardware being fitted on a data centre server cabinet

When choosing the correct latch, you'll need to match the IP or NEMA rating of the enclosure. Two examples are NEMA 4x electrical enclosures (washdown duty rating) and the NEMA 3R electrical enclosure designation (rain tight, dust proof). The latch rating must match so that the enclosure is not de-rated.

There are several dimensions to be aware of in order to ensure a snug, gap-free fit between the door and the enclosure cabinet.

In the dimension sizing example below, the head height is the least important.

A hinged electrical junction box or equipment enclosure door will normally mate with the surface of the cabinet or enclosure, often sealing over a vertical lip. However, some enclosures are made with recessed doors, making contact with an inner lip built into the box.

In either case, this is one of the first dimensions you need to properly size the cam lock. Determine the distance between the outer surface of the door and the inner surface of the enclosure where the cam will make contact. This dimension ensures a snug fit.

This will determine the housing height, also called the barrel length.

Dimension Sizing Example
Dimension To Be Measured
Example Dimension
Grip Range 1.063 - 2.835 in
Head Height 0.984 in
Housing Height 1.26 in
Maximum Compression 0.236 in
Maximum Grip 2.835 in
Maximum Panel Thickness 0.709 in
Minimum Grip 1.063 in

The actual thickness of the door is not usually an issue in metal enclosure because the barrel of the latch is threaded and secured with a locking nut. However, the maximum panel thickness may be important if the door is made of wood or other thick materials.

In the above example, you see the grip range dimensions. Often this is adjustable, and its main purpose is to allow for the gasket used (if any) to seal the door. Note that the grip range has a maximum and minimum grip dimension.

Maximum compression also plays into the snugness of the door to the enclosure’s fit.

The barrel or housing must be matched to the latch hole in pre-punched doors. Most barrels are round and have a threaded diameter to accept the locking nut but are also flat on opposing sides to prevent the latch from turning in the mounting hole.

Worker tightening a compression latch ready for installation on an application

Other cam lock considerations

Often the compression can be adjusted when the door is closed by rotating the latch knob. This type of design makes it easier to close the latch and then tighten the seal.

Handles for cam locks come in a variety of configurations:

The configuration you choose is determined by how often the enclosure is accessed, how secure you need the enclosure to be (e.g., authorised personnel only), and whether you need a low-profile latch to prevent damage from personnel traffic.

You may need to specify a lockable latch, often a keyed one. However, you can use a tamper resistant latch that requires a special tool to open it.

Low profile lift and latch cam locks will add another dimension to consider. Doors that accept these latches will have a rectangular hole cut or punched into them instead of the rounded hole. Take that dimension as well when choosing or specifying your electrical enclosure locks and latches.

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