How Does a Commercial Master Key System Work?

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Image 1: Pin tumbler with key

This may have something to do with the fact that we tend to geek out at Holicong over complicated security apparatuses, but we’ve always considered commercial master keys to be imbued with a certain sort of mystery. Maybe even a little romance.

After all, we’re talking about a key that can access every last lock in a multimillion-dollar skyscraper. A key that’s capable of opening every door in a sports stadium. A master key is a curious thing, and it’s a very powerful thing. You’d certainly never want to let a commercial master key fall into the wrong hands. It’s a key that offers access to every locked office, room and storage space in buildings where fortunes can be made and lost in the space of a day.

Those are just a few of the reasons so many of us find master keys so fascinating. And yet none of them truly represent the real reason they intrigue security enthusiasts. What is the real reason? It’s this: Managing to understand exactly how a commercial master key system works is a complicated process. Take it from those of us who work with locks every day: Figuring out the mechanics of master keys can be confusing to the extreme. But not to worry: They can indeed be explained plainly and understood clearly.

Could a Master Key System Make Your Life a Little Simpler?

We hope that by laying out the basics of how these powerful tools work, we will also help you decide whether a master key system might be a wise investment for your commercial property. The installation, at least when carried out by qualified professionals, isn’t necessarily cheap, although it’s much more affordable than you’d probably figure. The payoff, of course, can prove to be well worth the initial investment and then some. If you’d like a professional opinion about your own unique circumstance, get in touch with the Holicong Security team today.

Understanding Cylindrical Locks

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Image 2: Pin tumbler unlocked, image courtesy of

The bottom line is this: You’ll never understand how a master key system works without first understanding the basic mechanics of a standard, one-key lock, like the one in your home’s front door. These sorts of locks are known as cylindrical locks.

We’ll be the first to admit that without a video or some sort of image, explaining the operational process of a lock is pretty tough. Start, therefore, by studying the images below, which illustrates how a lock cylinder contains two sets of pins.

There’s a lower set (key pins), which get ever-so-slightly raised when they’re met by the ridges of your key. And there’s an upper set (driver pins), which are held in place by springs, and are raised when the lower pins push them up.  Assuming you’ve inserted the correct key into the right lock, the two sets of pins will meet at a center ridge line known as a shear line. When the shear line is created, or ‘cleared,’ the barrel can turn, which allows the lock to open. (For a slightly different visual perspective, take a look at this video.)

How Are Master Key Systems Different?

Given the complicated design of even the most basic key systems, it’s perhaps surprising that a master key system isn’t all that different. We found a very clear and concise explanation of the differences on the United Locksmith blog, which explained it like this:

“All that is needed for any standard pin tumbler to be converted for a master key system is to add a master wafer (aka master pin) between [the] driver [pin] and [the] key pin. A master wafer is virtually a small, hockey puck-shaped pin. Once [the master wafer] is in place, the pin stack will have two shear lines: A shear line for a pin stack with a master wafer below or above the line.”

Still confused? Take a look at the illustration below, and you’ll see how two shear lines can be created with the addition of master wafers: One along the top line of the master wafers, and another along the bottom. Pretty clever, no?

commercial master key diagram

A commercial master key system diagram, courtesy of

Grand Master Keys and More

There is, of course, a whole lot more to learn about keying systems than the basic subjects we’ve touched on here. And so just to pique your interest a bit more, we’d like to leave you with a fun fact: Did you know it’s possible to have keys made that are much more powerful than a master key? It’s true.

There are, for instance, keys known as grand master keys, which are used to access any number of master key systems. A developer with a portfolio of dozens of commercial properties, in other words, could have a grand master keying system installed in each of his or her properties, which would allow every lock in every building to be opened by the same key.

Not impressive enough? How about a great grand master key, which opens every lock in every grand master key system within it, as well as the master key systems and change key locks (single key locks) within those? Presumably, a developer with properties scattered throughout the world might want one special key that opens every lock to every door in every building with his name on it. That’s not a key you’d want to lose!

Considering a Commercial Master Key System for Your Property?

Hopefully we’ve succeeded in opening your eyes to the convenience and simplicity a master key system can offer. If you’d like to learn more about how the experienced technicians at Holicong Security can help you bring this very cost-effective form of access control into your business and your life, get in touch with us today. We think you’ll be pleasantly surprised by the enormous difference a high-quality, customized master key system can make.

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