Safety Switch v. Disconnect.

Any difference?

Light fixture v. Luminaire

any difference?

ARTICLE 530 Motion Picture and Television Studios and Similar Locations

530.2
Bull Switch.

An externally operated wall-mounted safety switch that may or may not contain overcurrent protection and is designed for the connection of portable cables and cords.

the term "disconnect switch" is used in 527, 550, and 620

I believe the correct term should be as defined in Article 100:

Disconnecting Means. A device, or group of devices, or other means by which the conductors of a circuit can be disconnected from their source of supply.

So then a safety switch would be a manually operated switch, while a disconnect could be the contactor?

TW

edited to add the confused

[This message has been edited by Trainwire (edited 01-03-2003).]

A disconnect could be a physical disconnection of an assembly of conductors
from a circuit also (EG a plug/receptacle).

I don't think a contacor could be used as a disconnect, as a disconnect is intended to be for safety purposes used.

Not "disconnecting means", but a
"Disconnect Switch v. Safety Switch"
You know, the gray metal box with the handle and the words "On" & "Off". Sometimes fusible(FSS), sometimes not (NFSS).

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

John

Redsy,

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!

Scott

Just to add to the confusion, in the U.K. the most commonly used term here would be "isolator."

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

would a LOTTO compliant disco as opposed to one that was not apply here?

All,
I truly am wondering if there are 2 different pieces of equipment, or if either term can be accurately used to describe what we commonly refer to as a "disconnect".
pauluk,
In the US an "Isolating Switch" refers to a switch that is not used to interrupt load current, but to provide a means to isolate the power from the load after it has been disconnected by other means.
(Sounds like a good definition for a safety switch to me?)

More confusion

I often install receptacles that are switch and/or horsepower rated.

At the touch of a button and all conductors are opened and a spot for LOTO

Then you can close under load.

To me this is a disconect.
http://www.meltric.com/products.html

Here is how Graybar defines the terms, as indicated by the way they fill orders:
Safety Switch: Looks like a motor starter enclosure, with a big, lockable external handle.
Disconnect (non fused): Quite a bit smaller, with a flip-up front panel, that exposes something that looks like a circuit breaker, but without any amp rating on the little handle.

I did 12 fusible 3P-3Ø 60A's today. They were GE, and said "Safety Switch" on the cover.
So, what's an EXO?

Electure — That's short for "externally operable" such as a fusible switch where you don’t lift a cover to operate it. Another term is "XOP."