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Old 11-08-2014, 05:56 PM   #31
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I was looking at Art. 440 and thought this might apply. On a 20 amp circuit the A/C needs to be under 10 amps or an interlock installed.

440.62 (C)Where Lighting Units or Other Appliances Are Also Supplied. The total marked rating of a cord-and-attachment plug-connected room air conditioner shall not exceed 50 percent of the rating of a branch circuit where lighting outlets, other appliances, or general-use receptacles are also supplied. Where the circuitry is interlocked to prevent simultaneous operation of the room air conditioner and energization of other outlets on the same branch circuit, a cord-and-attachmentplug-connected room air conditioner shall not exceed 80 percent of the branch-circuit rating.
Here you go
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Old 11-09-2014, 12:26 AM   #32
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Here you go
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Old 11-09-2014, 01:25 AM   #33
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I have to say that Jake does have a valid point. From the looks of it boils down to whether or not the heaters is considered to be an appliance per NEC definition or not.

I am still leaning toward letting the AC go up to 80% of the circuit and not having an interlock since the supply does not give power to lighting or receptacle outlets... however if the heater falls under as such the earlier would apply.
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Old 11-09-2014, 01:40 AM   #34
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I guess it boils down to a heater meeting this definition?:
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Old 11-09-2014, 04:15 AM   #35
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In our raised ranch home, we have a wall mounted A/C, in the living-room. It is serviced by a 20 amp 240 volt breaker, directly in the service panel. The conductors are in BX cable, 10/3, with the bonding strip running within it. There are no splices between the service panel and the A/C. The BX cable runs along the floor of the attic.

This is would I would like to do: I want to install a heater in our bathroom ceiling (the other side, of which, is the attic). I would like to be able to use this source of power (A/C circuit) for that purpose. There will never be a time when the A/C will be running and heat will be needed in the bathroom.

My thinking is to create two 20 amp 120 volt circuits from the one 20 amp 240 volt line, already in the attic.

I need to know the proper way to achieve this.
Your AC unit runs on strictly 240 volts. It does not use a neutral wire. Yet you say the BX cable is 10/3. If it is 10/3 wire then there must be a white wire in that BX cable. You say you want to tap in on that line to service another load which is 120v. You will need to be sure that the white wire (if present) is not being used as an EGC at the AC plug. It should not be, but you never know what people do. Once you determine that the white wire is NOT being used at the 240v AC plug, you want to cut into that 10/3 BX wire with a good size 1900 box. Tie the red and black wire back to the AC line and leave the white wire disconnected to the AC plug, it is not needed. Select either the black or red junction wires and hook the 2 wire circuit going to the heater to the black wire and pick up the white to white from the feed. NOW what you have created is a circuit which is servicing a 240v load and a 120v load. Although each circuit is protected by the circuit breakers and have a handle tie, the question remains, is it code to have a 240v load and a 120v load at the same time? That is the question.
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Old 11-09-2014, 05:59 AM   #36
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Your AC unit runs on strictly 240 volts. It does not use a neutral wire. Yet you say the BX cable is 10/3. If it is 10/3 wire then there must be a white wire in that BX cable. You say you want to tap in on that line to service another load which is 120v. You will need to be sure that the white wire (if present) is not being used as an EGC at the AC plug. It should not be, but you never know what people do. Once you determine that the white wire is NOT being used at the 240v AC plug, you want to cut into that 10/3 BX wire with a good size 1900 box. Tie the red and black wire back to the AC line and leave the white wire disconnected to the AC plug, it is not needed. Select either the black or red junction wires and hook the 2 wire circuit going to the heater to the black wire and pick up the white to white from the feed. NOW what you have created is a circuit which is servicing a 240v load and a 120v load. Although each circuit is protected by the circuit breakers and have a handle tie, the question remains, is it code to have a 240v load and a 120v load at the same time? That is the question.

Absolutely fine. As long as the breaker is a double pole (I believe you need internal common trip , but I will double check that) it can serve both 120 and 240 volt loads.

They even make outlets for that:
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Old 11-09-2014, 06:10 AM   #37
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Ok, double checking he will need a double pole breaker with internal common trip if both 120 and 240 volt loads are present on the circuit. So a standard off the shelf double pole breaker will work for this.


(PS, ignore the grey highlights. Those are personal references for other stuff)
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Splitting a 240 circuit into two 120 volt circuits-breaker.jpg   Splitting a 240 circuit into two 120 volt circuits-breaker2.jpg  

Last edited by Jump-start; 11-09-2014 at 06:13 AM. Reason: adding PS
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Old 11-09-2014, 06:11 AM   #38
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Absolutely fine. As long as the breaker is a double pole (I believe you need internal common trip , but I will double check that) it can serve both 120 and 240 volt loads.

They even make outlets for that:
Holy Moley, I never saw an outlet like that. Yup, then no problem as long as there is a handle tie. Good one, thanks.
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Old 11-09-2014, 06:18 AM   #39
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Holy Moley, I never saw an outlet like that. Yup, then no problem as long as there is a handle tie. Good one, thanks.
They make everything. Ill show you another.

As long as the breaker has internal common trip he will be to code. Handle ties wont work when feeding both.
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Old 11-09-2014, 06:24 AM   #40
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Originally Posted by Jump-start View Post
Ok, double checking he will need a double pole breaker with internal common trip if both 120 and 240 volt loads are present on the circuit. So a standard off the shelf double pole breaker will work for this.


(PS, ignore the grey highlights. Those are personal references for other stuff)
But wait a minute, one load he has is line to line and one load is line to neutral. #1 deals with 2 line to neutral loads and #2 deals with line to line loads. I don't see where it says a combo of both. Although that outlet seems to have both a line to line and line to neutral. If the line to neutral load is high and the line to line load comes on, one line is going to be stressed out so the total load for bith the line to neutral and line to line can't be very much. Just seems weird though.
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Old 11-09-2014, 06:32 AM   #41
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But wait a minute, one load he has is line to line and one load is line to neutral. #1 deals with 2 line to neutral loads and #2 deals with line to line loads. I don't see where it says a combo of both. Although that outlet seems to have both a line to line and line to neutral. If the line to neutral load is high and the line to line load comes on, one line is going to be stressed out so the total load for bith the line to neutral and line to line can't be very much. Just seems weird though.


1,2,3, and 4 are exceptions to situations where a breaker needs both manual and automatic trip. In this case its neither line-line or line-neutral only so both do not apply.

You are correct though, when wired via a single circuit those outlets generally only support one and less of the other, however you could break the tabs and put 2 circuits on the same yoke.
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Old 11-09-2014, 06:38 AM   #42
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If curious the outlet wiring, scroll to "instruction sheet":

http://www.leviton.com/OA_HTML/Produ...minisite=10251
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Old 11-09-2014, 08:07 AM   #43
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I guess it boils down to a heater meeting this definition?:
I'd say yes.
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