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#19801 - 01/03/03 07:11 AM What's in a word?
Redsy Offline

Registered: 03/28/01
Posts: 2138
Loc: Bucks County PA
Safety Switch v. Disconnect.

Any difference?

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#19802 - 01/03/03 07:14 AM Re: What's in a word?
Pearlfish Offline

Registered: 09/12/02
Posts: 83
Loc: Chicago Ridge, Il, USA
Light fixture v. Luminaire

any difference?

#19803 - 01/03/03 07:23 AM Re: What's in a word?
Joe Tedesco Offline

Registered: 10/07/00
Posts: 3325
Loc: Boston, Massachusetts USA
ARTICLE 530 Motion Picture and Television Studios and Similar Locations

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.
Joe Tedesco, NEC Consultant

#19804 - 01/03/03 07:46 AM Re: What's in a word?
Trainwire Offline

Registered: 03/15/02
Posts: 364
Loc: Strasburg,PA,USA

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


edited to add the confused

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

#19805 - 01/03/03 08:08 AM Re: What's in a word?
classicsat Offline

Registered: 11/23/02
Posts: 449
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.

#19806 - 01/03/03 10:58 AM Re: What's in a word?
Redsy Offline

Registered: 03/28/01
Posts: 2138
Loc: Bucks County PA
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).

#19807 - 01/03/03 11:32 AM Re: What's in a word?
HotLine1 Offline


Registered: 04/03/02
Posts: 6792
Loc: Brick, NJ USA
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


#19808 - 01/03/03 12:36 PM Re: What's in a word?
Scotts Offline

Registered: 01/17/02
Posts: 224
Loc: Ventura, CA, USA

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!


#19809 - 01/03/03 01:52 PM Re: What's in a word?
pauluk Offline

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
Just to add to the confusion, in the U.K. the most commonly used term here would be "isolator."

#19810 - 01/03/03 02:38 PM Re: What's in a word?
JBD Offline

Registered: 07/12/01
Posts: 599
Loc: WI, USA
I believe, the term safety switch was coined by Square D to describe the safety provided by their enclosed disconnect switch.
Go to 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

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