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Old 04-19-2019, 02:08 PM   #21
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Originally Posted by nherndon View Post
Technically you can size the circuit breaker to the exact size and install a lockout in the panel itself. Then you would not need a serviceable disconnect at the outdoor unit either.
I have never heard of that, what code section?

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Why is it more important to make it convenient for someone that might be servicing the equipment in the future, than it is to make it convenient to the installer?
You can ask this same question about every instance of a safety disconnect being required.

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Furthermore if you are servicing the indoor unit why would you not also be servicing the outdoor unit.
Because the issue might only be with the indoor unit...?
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Old 04-19-2019, 02:12 PM   #22
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I ask you guys that install switches at the indoor unit to tell me what type of switches you are using. Most switches I have seen have been standard switches which in many cases is a violation. Many of these mini splits have a dc motor and an ac switch is non-compliant and can be dangerous. Apparently, if you turned the switch on under load you will get a big surprise.
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Old 04-19-2019, 02:14 PM   #23
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Here is a short read on ac vs dc switches

https://www.mouser.com/blog/which-sw...f-its-ac-or-dc
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Old 04-19-2019, 02:17 PM   #24
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Is it possible that the inside unit already has a plug in on the motor so it can be removed for servicing? I have never had one that far apart
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Old 04-19-2019, 02:37 PM   #25
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I ask you guys that install switches at the indoor unit to tell me what type of switches you are using. Most switches I have seen have been standard switches which in many cases is a violation. Many of these mini splits have a dc motor and an ac switch is non-compliant and can be dangerous. Apparently, if you turned the switch on under load you will get a big surprise.
I don't know anything about the motor, I never read that I had to worry about it in code. Only that I needed to disconnect the power to the unit.
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Old 04-19-2019, 02:51 PM   #26
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Re: AC vs DC head unit switches. The unit is fed with AC (typ 208 or 240 AC). If there is a DC motor internal, then it is power from an internal rectified source. AC switch will be correct to control the incoming feed.
Switch types? Leviton MS-302-DS, MS-303-DS.
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Old 04-19-2019, 03:18 PM   #27
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Originally Posted by nherndon View Post
Technically you can size the circuit breaker to the exact size and install a lockout in the panel itself. Then you would not need a serviceable disconnect at the outdoor unit either. So to me it does not make sense to have a disconnect at the indoor unit of the system. Why is it more important to make it convenient for someone that might be servicing the equipment in the future, than it is to make it convenient to the installer? Furthermore if you are servicing the indoor unit why would you not also be servicing the outdoor unit. I could argue the ladder or the two is more important, but I'm not and HVAC guru.
Do you have a code reference for not requiring a disco with in sight for a heat pump or condensing unit?
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Old 04-19-2019, 03:23 PM   #28
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Originally Posted by Lioneye View Post
Re: AC vs DC head unit switches. The unit is fed with AC (typ 208 or 240 AC). If there is a DC motor internal, then it is power from an internal rectified source. AC switch will be correct to control the incoming feed.
Switch types? Leviton MS-302-DS, MS-303-DS.
Never thought about that. I wonder why those engineers all said that a dc switch was needed.....
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Old 04-19-2019, 03:23 PM   #29
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Is it possible that the inside unit already has a plug in on the motor so it can be removed for servicing? I have never had one that far apart
Most have a plug that connects to the pc board that has plenty of circuitry that would be hard to have your fingers avoid if you were going to try and unplug the motor or pump.
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Old 04-19-2019, 03:27 PM   #30
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2014 nec

Quote:
422.31 disconnection of permanently connected appliances.

(a) rated at not over 300 volt-amperes or 1∕8 horsepower. For permanently connected appliances rated at not over 300 volt-amperes or 1⁄8 hp, the branch-circuit overcurrent device shall be permitted to serve as the disconnecting means.
2017 nec

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422.31 disconnection of permanently connected appliances.

(a) rated at not over 300 volt-amperes or 1∕8 horsepower. For permanently connected appliances rated at not over 300 volt-amperes or 1∕8 hp, the branch-circuit overcurrent device shall be permitted to serve as the disconnecting means where the switch or circuit breaker is within sight from the appliance or is lockable in accordance with 110.25.
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Old 04-19-2019, 03:29 PM   #31
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Originally Posted by Dennis Alwon View Post
I ask you guys that install switches at the indoor unit to tell me what type of switches you are using. Most switches I have seen have been standard switches which in many cases is a violation. Many of these mini splits have a dc motor and an ac switch is non-compliant and can be dangerous. Apparently, if you turned the switch on under load you will get a big surprise.
First of all the switch is on incoming power from the outdoor unit which is a/c on the units I've wired up.

As for under load, there is normally a thermostat on the refrigerant lines or coil or a timer that only turns on the fan after the coil or tubing is cold or after a designated time.
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Old 04-19-2019, 03:31 PM   #32
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Never thought about that. I wonder why those engineers all said that a dc switch was needed.....
They are engineers, the motor is dc.

Why do they need to actually read a schematic and see where the dc source is derived?
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Old 04-19-2019, 05:27 PM   #33
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First of all the switch is on incoming power from the outdoor unit which is a/c on the units I've wired up.

As for under load, there is normally a thermostat on the refrigerant lines or coil or a timer that only turns on the fan after the coil or tubing is cold or after a designated time.


so if I'm reading your rebuttal correctly the outdoor unit controls the indoor unit. so type of switch is irrelevant because the indoor unit will NEVER be under load unless the outdoor unit is commanding for it correct? so doesn't that also state that the means of disconnect of the indoor unit would be equally as useless?
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Old 04-19-2019, 05:56 PM   #34
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so if I'm reading your rebuttal correctly the outdoor unit controls the indoor unit. so type of switch is irrelevant because the indoor unit will NEVER be under load unless the outdoor unit is commanding for it correct? so doesn't that also state that the means of disconnect of the indoor unit would be equally as useless?
Nope. the outdoor unit is fed first and sends line voltage inside but the indoor unit has the low voltage board that controls operation.

As for the indoor disco, like I said its an air handler and often is serviced long before one ever goes out to try and locate the outdoor unit.

Think in terms of large buildings with multiple units as opposed to a house with one or two outdoors units right on the other side of the wall from the indoor unit.
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Old 04-19-2019, 06:01 PM   #35
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Nope. the outdoor unit is fed first and sends line voltage inside but the indoor unit has the low voltage board that controls operation.

As for the indoor disco, like I said its an air handler and often is serviced long before one ever goes out to try and locate the outdoor unit.

Think in terms of large buildings with multiple units as opposed to a house with one or two outdoors units right on the other side of the wall from the indoor unit.


This was at a large facility, however i apologize for arguing. That's not why i joined this forum. I respect everyone's answers and opinions. even when i don't agree with them. Thanks to everybody that had input, and have a great weekend guys!!
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Old 04-19-2019, 06:06 PM   #36
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This was at a large facility, however i apologize for arguing. That's not why i joined this forum. I respect everyone's answers and opinions. even when i don't agree with them. Thanks to everybody that had input, and have a great weekend guys!!
I don't see any argument, just textual discussion.

Enjoy your weekend.
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Old 04-19-2019, 10:22 PM   #37
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I believe the conversion from ac to dc is done in the condensing unit- the outdoor unit so it is DC going to the indoor unit. At least that is what I saw on one system.
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Old 04-19-2019, 10:34 PM   #38
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I believe the conversion from ac to dc is done in the condensing unit- the outdoor unit so it is DC going to the indoor unit. At least that is what I saw on one system.
Never seen that in any unit I've installed.

The power coming to the indoor unit provides 208/240 for the vacuum condensate pump, louvre motor, not just the indoor fan.
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Old 04-20-2019, 02:57 AM   #39
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2014 nec



2017 nec

2ND TIME TODAY I HAD TO SAY THIS. SLOWLY READ ARTICLE 440.3 (B). Split systems incorporate a hermetically sealed compressor and are exempt from Article 422,424, or 430. Air conditioners that do not have a hermetically sealed compressor motor are subject to those other Articles.
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Old 04-20-2019, 03:02 AM   #40
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Do you have a code reference for not requiring a disco with in sight for a heat pump or condensing unit?
440.8- single machine. Single machine= 1 disconnect. 2 exceptions in that section allow the motors to be remote from each other. Still 1 unit.
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