AC disco

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jumper

Senior Member
Where is your neutral and what OCPD protects the tap and receptacle? Tapping a 3 wire 30A 240V resi disco to a 15A 120V receptacle is a no no.

I am assuming you mean 3 wire was 2H+1G, no noodle.
 
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kwired

Electron manager
Location
NE Nebraska
Can a three wire be run to a disco for a 240vac AC unit and the receptacle requirement within 25' taken off of one leg?

Yes, and no.

If you are supplying a 240 volt A/C unit and a 120 volt receptacle you will need separate neutral and equipment ground in the supply.

If the overcurrent protection is 15 or 20 amps that may be all you need, if overcurrent protection is over 20 amps you will need to include 15 or 20 amp overcurrent protection for the required receptacle portion of this at the very least, some will say you need to treat this supply as a feeder and provide separate overcurrent devices for the A/C as well as for the receptacle.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Yes, and no.

If you are supplying a 240 volt A/C unit and a 120 volt receptacle you will need separate neutral and equipment ground in the supply.

If the overcurrent protection is 15 or 20 amps that may be all you need, if overcurrent protection is over 20 amps you will need to include 15 or 20 amp overcurrent protection for the required receptacle portion of this at the very least, some will say you need to treat this supply as a feeder and provide separate overcurrent devices for the A/C as well as for the receptacle.

Why would you need a separate egc? I am not sure you meant to say that.
 

kwired

Electron manager
Location
NE Nebraska
Why would you need a separate egc? I am not sure you meant to say that.

From what is said in OP he has 240 volt AC and a three wire (cable) and wants to also supply a 120 volt receptacle, how does he get a neutral for the receptacle in a proper way with only a three wire cable?
 

jumper

Senior Member
From what is said in OP he has 240 volt AC and a three wire (cable) and wants to also supply a 120 volt receptacle, how does he get a neutral for the receptacle in a proper way with only a three wire cable?

We are all saying the same thing here, just different ways:

2H+1G=no.

2H+1N+1G=yes, assuming proper sizing and OCPDs are provided.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
Yes, and no.

If you are supplying a 240 volt A/C unit and a 120 volt receptacle you will need separate neutral and equipment ground in the supply.

If the overcurrent protection is 15 or 20 amps that may be all you need, if overcurrent protection is over 20 amps you will need to include 15 or 20 amp overcurrent protection for the required receptacle portion of this at the very least, some will say you need to treat this supply as a feeder and provide separate overcurrent devices for the A/C as well as for the receptacle.

Why would you need a separate egc? I am not sure you meant to say that.

From what is said in OP he has 240 volt AC and a three wire (cable) and wants to also supply a 120 volt receptacle, how does he get a neutral for the receptacle in a proper way with only a three wire cable?

I think Dennis was just asking why a separate EGC, not the neutral. He knows you need the neutral. Just my take on it.
 

kwired

Electron manager
Location
NE Nebraska
I think Dennis was just asking why a separate EGC, not the neutral. He knows you need the neutral. Just my take on it.

Maybe I need to clarify what I said. When I used the word separate I meant separate neutral and equipment grounding conductor not two different equipment grounding conductors.
 

renosteinke

Senior Member
Location
NE Arkansas
I once thought this application over, and the solution is .... ELIMINATE the disconnect. Well, sort of.

Instead, spend just about the same amount of money on a 4-space panel. Use the breaker in this panel as the disconnect for the HVAC, and use another space to feed the receptacle.

No double-lugging, no shortage of wire space, no question of what to do with the neutral.

You still need a 4-wire feed, though.
 
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