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#19801 01/03/03 11:11 AM
Joined: Mar 2001
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Redsy Offline OP
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Safety Switch v. Disconnect.

Any difference?

#19802 01/03/03 11:14 AM
Joined: Sep 2002
Posts: 83
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Light fixture v. Luminaire

any difference?

#19803 01/03/03 11:23 AM
Joined: Oct 2000
Posts: 2,749
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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.


Joe Tedesco, NEC Consultant
#19804 01/03/03 11:46 AM
Joined: Mar 2002
Posts: 360
T
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[Linked Image]

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).]

#19805 01/03/03 12:08 PM
Joined: Nov 2002
Posts: 456
C
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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 02:58 PM
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Redsy Offline OP
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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 03:32 PM
Joined: Apr 2002
Posts: 7,381
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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


John
#19808 01/03/03 04:36 PM
Joined: Jan 2002
Posts: 209
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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

#19809 01/03/03 05:52 PM
Joined: Aug 2001
Posts: 7,520
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Just to add to the confusion, in the U.K. the most commonly used term here would be "isolator."

#19810 01/03/03 06:38 PM
Joined: Jul 2001
Posts: 599
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JBD Offline
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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

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