Disconnect/Safety Switches
- Thread starter cjadams
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- Location
- Lockport, IL
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- Semi-Retired Electrical Engineer
Re: Disconnect/Safety Switches
Any term used in the NEC, but not explicitly defined in the NEC, should be interpreted by ?industry standard usage? of that term. But if you are asking for a reference book that you can cite, in order to settle a disagreement, I do not have any that I can recommend to you.
Are you asking for a list of circumstances in which the NEC requires a ?disconnect,? as opposed to requiring a ?fused disconnect?? If this is your question, then I don?t think you will find either. The NEC requires a ?disconnecting means? in several circumstances, and a breaker, disconnect, fused disconnect, and safety switch can satisfy those requirements. The NEC also requires over-current protection in several circumstances. A breaker or fused disconnect can satisfy those requirements, but neither an unfused disconnect nor a safety switch would suffice. A fused disconnect can satisfy the requirements for a disconnecting means and for over-current protection, in a single device.
If that did not answer your question, may I ask you to give us more details concerning the problem you are trying to solve?
Any term used in the NEC, but not explicitly defined in the NEC, should be interpreted by ?industry standard usage? of that term. But if you are asking for a reference book that you can cite, in order to settle a disagreement, I do not have any that I can recommend to you.
Are you asking for a list of circumstances in which the NEC requires a ?disconnect,? as opposed to requiring a ?fused disconnect?? If this is your question, then I don?t think you will find either. The NEC requires a ?disconnecting means? in several circumstances, and a breaker, disconnect, fused disconnect, and safety switch can satisfy those requirements. The NEC also requires over-current protection in several circumstances. A breaker or fused disconnect can satisfy those requirements, but neither an unfused disconnect nor a safety switch would suffice. A fused disconnect can satisfy the requirements for a disconnecting means and for over-current protection, in a single device.
If that did not answer your question, may I ask you to give us more details concerning the problem you are trying to solve?
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Re: Disconnect/Safety Switches
Technically there is no difference other than the spelling.
"Safety switch" usually refers to an individually mounted enclosed disconnect switch.
A more important question is the difference between load break and non-load break ratings.
Technically there is no difference other than the spelling.
"Safety switch" usually refers to an individually mounted enclosed disconnect switch.
A more important question is the difference between load break and non-load break ratings.
Re: Disconnect/Safety Switches
I believe your question has been answered by the previous posts. I would like to point you in the direction of serveral switch manufacturers. If you look at Square D Digest, GE Buylog or Cutler Hammer application guide you would find that all of these switch manufacturer's catalog "Safety Switches". It doesn't matter whether they are general or heavy duty, or if they are fused or non-fused.
I believe your question has been answered by the previous posts. I would like to point you in the direction of serveral switch manufacturers. If you look at Square D Digest, GE Buylog or Cutler Hammer application guide you would find that all of these switch manufacturer's catalog "Safety Switches". It doesn't matter whether they are general or heavy duty, or if they are fused or non-fused.
bphgravity
Senior Member
- Location
- Florida
Re: Disconnect/Safety Switches
The term "safety switch" is to differentiate it from a general-purpose open switch. Although uncommon today, Open switches have their current-carrying parts exposed. An example would be a open knife-blade switch enclosure. Safety switches on the other hand have all current-carrying parts concealed or covered. Many safety switches have interlocked doors that do not allow operation with the door open.
The term "safety switch" is to differentiate it from a general-purpose open switch. Although uncommon today, Open switches have their current-carrying parts exposed. An example would be a open knife-blade switch enclosure. Safety switches on the other hand have all current-carrying parts concealed or covered. Many safety switches have interlocked doors that do not allow operation with the door open.
Re: Disconnect/Safety Switches
this goes back a ways but I always thought a safety switch was one that allowed power to be disconnected from what it is/was protecting, with fuse or breaker that allowed for protection of lines/equipment. I don't know where it is defined. I always heard/saw fused lockout type knife switches referred to as safety switches.
paul
this goes back a ways but I always thought a safety switch was one that allowed power to be disconnected from what it is/was protecting, with fuse or breaker that allowed for protection of lines/equipment. I don't know where it is defined. I always heard/saw fused lockout type knife switches referred to as safety switches.
paul
caosesvida
Senior Member
Re: Disconnect/Safety Switches
I think the safety part was when they enclosed the switch instead of open mounted on a wall.Like in the knob and tubing style. I have a 200 amp panel that is made of slate, with 30 amp knife switches as the circuit disconnects, all completely exposed and very close to each other..Looks like something from a frankenstien lab. I wouldn't want to turn any of those off without gloves on!
I think the safety part was when they enclosed the switch instead of open mounted on a wall.Like in the knob and tubing style. I have a 200 amp panel that is made of slate, with 30 amp knife switches as the circuit disconnects, all completely exposed and very close to each other..Looks like something from a frankenstien lab. I wouldn't want to turn any of those off without gloves on!
bphgravity
Senior Member
- Location
- Florida
Re: Disconnect/Safety Switches
The American Electricians' Handbook 14th Edition provides a pretty good description of a safety verses open switching. Its a very generic term that can apply to many different designs of equipment used for switching.
The American Electricians' Handbook 14th Edition provides a pretty good description of a safety verses open switching. Its a very generic term that can apply to many different designs of equipment used for switching.
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