120 volt wiring in 240 disconnect box

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Old 04-16-19, 12:35 PM
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120 volt wiring in 240 disconnect box

I am wiring a disconnect box for a 12000 btu ductless ac system which only needs 120 volts. Can I wire the black wire to one line terminal and the white wire to the other line terminal with the ground connected to the ground bar in the disconnect? Thanks,
 
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Old 04-16-19, 01:03 PM
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Wirenut the neutrals together (separate from the grounds) and only use one pole of the disconnect switch for the hot. The other pole will be unused.
 
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Old 04-16-19, 01:19 PM
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Thank you for your reply. However, Is there any harm in wiring the way I mentioned above?
 
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Old 04-16-19, 02:06 PM
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Yes for safety purposes the neutral should not be disconnected by a switch. You only ever switch hot conductors.
 
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Old 04-16-19, 02:27 PM
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Thank you for the explaination!!!!
 
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Old 04-16-19, 03:28 PM
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There is no reason NOT to disconnect both the hot and the neutral. You will be fine as long as you switch both. You can not switch just the neutral however.
 
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Old 04-16-19, 05:52 PM
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Hi, itís best to wirenut the neutrals straight through as previously mentioned, white on the breaker would indicate a 240 volt supply.
Geo
 
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Old 04-16-19, 09:28 PM
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Code prohibits what the OP is proposing, and requires neutral connections to be independent of devices (one should even pigtail neutrals for receptacles instead of pass through wiring).

Geo,
I like this point. That is what my brain would shoot for if I opened this disconnect up and saw that.
 
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Old 04-18-19, 06:25 PM
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I don't know about codes in Canada, but I believe the NEC prohibits switching the neutral conductor except for when wiring gas pumps......And that may have changed in the latest versions.
 
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Old 04-18-19, 07:58 PM
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Switching ONLY the neutral and leaving the hot on is prohibited. No problem switching both.
 
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Old 04-18-19, 08:57 PM
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FYI, here's an article about switching the neutral by a UL engineer:

https://www.ecmag.com/section/codes-standards/switching-neutral-ok

Also, a requirement to pigtail the neutral for a receptacle was mentioned earlier in the thread. As far as I know, this is only required by the NEC in multiwire branch circuits (two hot wires on opposite phases with a shared neutral). Some local codes might have a more general requirement for this, however.

 
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Old 04-19-19, 09:23 AM
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We are getting a little off topic here, but in reference to switching the neutral conductor here are some Square D breakers that do just that.

https://www.schneider-electric.us/en/faqs/FA91446/


The OP was asking about a mini split A-C unit. In this application I definitely would not switch the neutral conductor.
 
 

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