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I was thinking it had to be one simulatious disconnecting means.

As long as the switches are 'grouped' it is no problem.

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I have seen weatherproof boxes full
of condensation inside walk-ins.

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Yes that is a common problem and it is caused by failing to comply with 300.7(A)

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300.7 Raceways Exposed to Different Temperatures.

(A) Sealing. Where portions of a cable raceway or sleeve are known to be subjected to different temperatures and where condensation is known to be a problem, as in cold storage areas of buildings or where passing from the interior to the exterior of a building, the raceway or sleeve shall be filled with an approved material to prevent the circulation of warm air to a colder section of the raceway or sleeve. An explosionproof seal shall not be required for this purpose.

If 300.7 is ignored you will get water.

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Is there any reason not to use conventional 4S boxes?

No not really.

For my work it is usually a customer requirement.

But it is not a problem if you follow 300.7 and make a small drain hole in the box all is good.

Just trimming a notch in the covers gasket at the bottom is enough to make sure the box does not fill with water.

Bob


Bob Badger
Construction & Maintenance Electrician
Massachusetts