Redsy: Are we splitting hairs??? The "gray box" with the handle, and "on/off" and capable of being locked in either position can be a "disconnect" or a "safety switch". A piece of equipment requires a disconnect switch within sight, the words are not "safety switch".
Either one can be fused or non-fused unless it it used for OCP, correct?
Now, here's a wrinkle.. the "pull out" devices that are commonly used at resi HVAC compressors, what should they be called?? Some of them can be locked (cover) after you "pull" the mechanism, and that satisfies the "lockable" requirement.
I'm not being a smart axx, but I don't see what the doifference can be.
Alas, we are all here to learn, and share info, and lord knows, I have a lot to learn
In my ignorant opinion I prefer the term disconnect to safety switch. The gray box with the handle disconnects the machine from the power source. The term safety switch is too vague for me.
When you throw the switch on the grey box you are disconnecting the machine from the electrical source, you are not making the machine safe. There are still numerous ways to get hurt from a machine, even if the switch on large gray box is in the off position.
Plus I learned the term disconnect and I don't want to change!
I believe, the term safety switch was coined by Square D to describe the safety provided by their enclosed disconnect switch. Go to http://www.squared.com/us/squared/corporate_info.nsf/unid/A21F52058A62BF0C85256A4C004CFBA2/$file/histsqdFrameset.htm for Square D's history.
In reality even the term "disconnect switch" is not defined. Disconnects (as a shortening of the term Disconnecting Means) are mentioned in th NEC but not specifically switches.
IMHO, If it is a switch, and it removes conductors from their source, then it is a disconnect switch. If it is also enclosed then it is a safety switch.
The only applicable standards I know of are: UL98 - Enclosed and Dead Front Switches and NEMA Standards Publication KS1 - Enclosed Switches