40 amp sub panel

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  #1  
Old 02-10-16, 06:34 PM
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Question 40 amp sub panel

hello, im planning on installing a 40amp breaker to a sub panel in my attached garage. inside the sub i want to have two 20amp breakers. this will only be used for 240v, with no plans for future upgrades, or every using anything 120v on the new panel.

can use 8/2 romex instead of 8/3? i will never use this for anything other than 240v.

want to use the two 20amps in the bow to power two 240v receptacles each..4 outlets. using 12/2.

anything wrong with this situation? looking for some advice


forgot to mention i already have the 8/2 wire. i just don't want to have to buy 8/3 if i dont need too.
 
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Old 02-10-16, 06:43 PM
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Yes you can use 8-2. .
 
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Old 02-10-16, 06:50 PM
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thank you so much ray. i have searched all over the internet for this answer. everyone is either planning to use 120v on their sub or the aren't and one of the replies says you shoulld just use 8/3 three in case of future up grades, the op says ok and the thread ends lol. never touching on if using 8/2 is ok if only running 240v haha

thank you very very much
 
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Old 02-10-16, 07:29 PM
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Never is a long time and what about when you sell the place or die? Even in commercial and industrial work the additional cost of running neutral conductors to panelboards is minimal and almost always done even if no phase-to-neutral loads are planned.
 
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Old 02-10-16, 07:43 PM
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the wire is already ran (8/2). it is ran to a single receptacle..?

i just want to use the existing 40amp breaker, and wire. remove the outlet and replace with 2 20 amp and have four 240v outlets.

i could piggy back 3 more outlets but i like the idea of a sub in the garage and splitting them up.

im dont wana have to run new wire and all that just a simple switch a roo

can write "240v only!!!" on the sub in case i die
 
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Old 02-10-16, 07:48 PM
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i would just hook the ground to the green screw and the two hots to the panel thing right.

no need for and extra bar and all the extra stuff usually needed to be done to the panel to run the the 8/3?

sorry i dont know all the proper terms. i just used to do all the grunt work for my uncle who was an electrician and picked up some stuff. he has passed so i cant ask him
 
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Old 02-10-16, 08:00 PM
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no need for and extra bar
You need a bonded ground bar for all ground wires. It would be up to the local inspector if he would let you repurpose the neutral bar. A new ground bar will probably be less than $5 so why pinch pennies.
 
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Old 02-10-16, 08:04 PM
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ok, got it. so there will be nothing connected to that neutral bar then right?
 
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Old 02-10-16, 08:20 PM
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That is correct. Nothing attached to the neutral bar and it should not have a bonding screw or strap. It needs to be isolated because this is not the first panel with an over current protection device (OCPD).
 
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Old 02-10-16, 08:27 PM
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ok thank you ray. you answered my next question about the screw and strap.

so remove screw, do not strap and install an extra separate bonded ground bar for the ground?

i will post pics when done, to make sure i'm a good to go.
 
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Old 02-10-16, 09:27 PM
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do not strap and install an extra separate bonded ground bar for the ground
Not sure what you mean. You need to install a separate bonded ground bar. All grounds go to it. Nothing goes to the neutral. My mention of strap related to bonding the neutral bar. Usually, depending on brand, a screw is used, occasionally a strap is used. Regardless of the method the neutral is not bonded. Any screw or strap is removed from the neutral bar.
 
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