×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

OF ac disconnect switch

OF ac disconnect switch

OF ac disconnect switch

(OP)
pls tell me where do we use Air conditioner disconnect switch ? i havent seen such a thing by now.

RE: OF ac disconnect switch

It should be within reach of the compressor or if the fan/ condenser is remote, within reach of it.  The point of it is to allow the mechanical equipment to be shut down without any confusion as to whether the "right" switch was thrown or not, and to allow rapid shut down if there's an accident or problem.

Keith Cress
kcress - http://www.flaminsystems.com

RE: OF ac disconnect switch

(OP)
so how does it happen that some of these switches has no breaker or fuse  , i mean if there is a fault and the line is not off really, can it be dangerous to open the switch? an arc perhAPS???

RE: OF ac disconnect switch

A disconnect and fault protection are different.  One is just to remove power for service or accident prevention.  The other is for automatic disconnection during fault conditons.

A disconnect CAN also be fault protection if it is a circuit breaker or has fuses associated with it.

A disconnect must be able to cut the power OFF to the machinery, so no, there should be no arc flash issues associated with a closed enclosure disconnect switch.  If the disconnect includes fuses they should be disconnected by operating the disconnect.  This would allow one to replace the fuses.  Of course if there is any  question about power still being present after operation of a disconnect you should use a voltmeter to test for it.

Keith Cress
kcress - http://www.flaminsystems.com

RE: OF ac disconnect switch

A fault condition will be disconnected immediately by the fuses or breaker. A high resistance fault may persist for some seconds. The fault does not wait for the serviceman to arrive and disconnect the power.
The mechanism used in an approved disconnect switch is rated to interrupt fault current in the rare event that the switch may be opened during a fault.
The code mandates that a disconnect must be installed within sight and within a certain number of feet of the equipment protected. There are exceptions.

Bill
--------------------
"Why not the best?"
Jimmy Carter

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources