ductless split hvac: indoor disconnect?

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bob purvis

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Ductless split system heat pumps like Mitsubishi, etc. have the indoor unit wired as a slave to the outdoor unit; ie. the power feed 115 volt, 2 wire, with 3rd wire signal wire, feeds from the outdoor unit to the indoor unit. These systems are usually supplied with instructions recommending that this power feed through the wall directly into the back of the indoor unit.

Since the outdoor unit has a disconnect next to it, that disconnects all power to the outdoor unit, and thus to the indoor unit, this would allow the indoor unit to be disconnected from power at the disconnect. Electrical inspectors are requiring that a disconnect means be installed indoors..usually on the wall next to the indoor wall mounted section of the heat pump.

If the outdoor disconect for this equipment has a cover that can be locked when disconnected, does this eliminate the need for a disconnect means inside next to the unit there?

It would seem that it should, as long as the indoor unit is a slave, ie gets its power directly from the outdoor unit, which can be shut down and locked at the outdoor disconnect.
 
bob purvis said:
Ductless split system heat pumps like Mitsubishi, etc. have the indoor unit wired as a slave to the outdoor unit; ie. the power feed 115 volt, 2 wire, with 3rd wire signal wire, feeds from the outdoor unit to the indoor unit. These systems are usually supplied with instructions recommending that this power feed through the wall directly into the back of the indoor unit.

Since the outdoor unit has a disconnect next to it, that disconnects all power to the outdoor unit, and thus to the indoor unit, this would allow the indoor unit to be disconnected from power at the disconnect. Electrical inspectors are requiring that a disconnect means be installed indoors..usually on the wall next to the indoor wall mounted section of the heat pump.

If the outdoor disconect for this equipment has a cover that can be locked when disconnected, does this eliminate the need for a disconnect means inside next to the unit there?

It would seem that it should, as long as the indoor unit is a slave, ie gets its power directly from the outdoor unit, which can be shut down and locked at the outdoor disconnect.
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No, it does not... that would only qualify under exception if, in short, the equipment is essential to an industrial process.

The disconnect has to be within sight and readily accessible from the equipment served.

Ref: 440.14 Location
 
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bob purvis said:
Electrical inspectors are requiring that a disconnect means be installed indoors..usually on the wall next to the indoor wall mounted section of the heat pump.

If the outdoor disconect for this equipment has a cover that can be locked when disconnected, does this eliminate the need for a disconnect means inside next to the unit there?

It would seem that it should, as long as the indoor unit is a slave, ie gets its power directly from the outdoor unit, which can be shut down and locked at the outdoor disconnect.
Click to expand...

Hi Bob

Welcome to the forum.

Article 430 is a good read for your line of work. Specifically 430.101 will address disconnecting means that are permitted for your specific example. The inspector is correct in that a disconnect is required to be in sight of the equipment.
 
Since they are back to back, run the feed thru a switch box facing the interior side first before you hit the exterior disconnect box. Put a rated switch in the interior one. Hook up the control feeder wires directly from the compressor to the fan coil. Presto, now you have a disconnecting method in direct line of site of the interior fan coil unit.
 
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