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Hermetic Motors, Part 3

Hermetic-Motors-Part-3Part II of Article 440 is all about the disconnecting means. One of the things it doesn’t tell you is this. If you service residential units, you may come across a disconnect that has been modified (damaged) by the homeowner.

Because of the way these disconnects typically open, the unskilled, untrained homeowner who is in a DIY mood is likely to force the device apart. Then, in an effort to get it back together, this non-electrician bends it and may leave it in a dangerous condition.

Unfortunately, the same problem exists in small commercial or industrial settings that lack a qualified maintenance force or where the owner decides to play electrical contractor for the day.

So before servicing any system with a hermetic motor, visually inspect the disconnect first. If it appears to be damaged, even slightly, notify the owner of the damage and provide a cost for the replacement. Putting your life at risk by trusting a damaged safety device is not worth it, so don’t accept “make do with it” for an answer.

Now, on to what Part II does tell you. Basically, the disconnect must be selected based upon the greater of the nameplate rated-load current or the branch-circuit current and the locked-rotor current. Part II goes into the details of determining the ampere rating of the disconnect. Typically, the system manufacturer will specify the disconnect rating. Locate the disconnect within sight.

« Part 2 | Source: Mark Lamendola | Mindconnection