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Old 04-24-2019, 02:54 PM   #1
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If it's 80 ft long wire (20amps) a considerable problem for voltage drop?


Hi there,
So I'm going to have 20 amps wire as long as 80 ft from the subpanel , via a junction box, to devices. Should I take "voltage drop" into consideration that it's best to install another subpanel instead of the junction box, although it cost me more to move the AC condenser which is now in the front of the junction box/subpanel location.

Thanks
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Old 04-24-2019, 04:41 PM   #2
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Re: If it's 80 ft long wire (20amps) a considerable problem for voltage drop?


should be fine - my house is over 80' long (panel is at one end) and no circuits have aver been affected by voltage drop...

found this:
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Last edited by KPDMinc; 04-24-2019 at 04:44 PM.
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Old 04-24-2019, 04:51 PM   #3
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Re: If it's 80 ft long wire (20amps) a considerable problem for voltage drop?


Quote:
Originally Posted by KPDMinc View Post
should be fine - my house is over 80' long (panel is at one end) and no circuits have aver been affected by voltage drop...

found this:
Thanks. My house is like 40 feet from subpanel to junction box, and then from junction box to all the outlet it can vary from 10 feet to 40 feet, so the total length is between 50 feet to 80 feet.

By the way, I'm in Los Angeles, is the power coming into the house 110V or 120V?
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Old 04-24-2019, 05:04 PM   #4
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Re: If it's 80 ft long wire (20amps) a considerable problem for voltage drop?


Quote:
Originally Posted by rockman413 View Post
Thanks. My house is like 40 feet from subpanel to junction box, and then from junction box to all the outlet it can vary from 10 feet to 40 feet, so the total length is between 50 feet to 80 feet.

By the way, I'm in Los Angeles, is the power coming into the house 110V or 120V?
have to measure to find out the actual voltage
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Old 04-24-2019, 05:15 PM   #5
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Re: If it's 80 ft long wire (20amps) a considerable problem for voltage drop?


Our code allows #12 to be used on a 20A breaker up to max length of
50m (164ft). While not code outside of Canada, this probably wouldn't
be a bad guide line.
Code ref Table 68.
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Old 04-24-2019, 05:50 PM   #6
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Nominal US voltage.is 120/240.
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Answers based on the National Electrical Code. Local amendments may apply. Check with your local building officials.
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Old 04-24-2019, 06:19 PM   #7
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Re: If it's 80 ft long wire (20amps) a considerable problem for voltage drop?


Quote:
Originally Posted by CodeMatters View Post
Our code allows #12 to be used on a 20A breaker up to max length of
50m (164ft). While not code outside of Canada, this probably wouldn't
be a bad guide line.
Code ref Table 68.
Is the outlet , which I think is a 20A circuit, normally is a Gauge 12 or Gauge 14 wire?
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Old 04-24-2019, 06:37 PM   #8
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Re: If it's 80 ft long wire (20amps) a considerable problem for voltage drop?


Quote:
Originally Posted by rockman413 View Post
Is the outlet , which I think is a 20A circuit, normally is a Gauge 12 or Gauge 14 wire?

20A breaker will normally feed #12 wire.
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Old 04-24-2019, 06:39 PM   #9
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Re: If it's 80 ft long wire (20amps) a considerable problem for voltage drop?


Quote:
Originally Posted by Jim Port View Post
Nominal US voltage.is 120/240.

Also be accurate to say North American nominal voltage is 120/240.
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Old 04-24-2019, 07:24 PM   #10
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Re: If it's 80 ft long wire (20amps) a considerable problem for voltage drop?


Quote:
Originally Posted by CodeMatters View Post
Also be accurate to say North American nominal voltage is 120/240.
So I'm having a 5volt voltage drop, I may end up at 115V, since most devices is made for 110V-120V, even I got this home run wires in my house up to 80 Feet, I'm still good because 115V is > 110V, am I correct?

So need to move the AC or do a subpanel, just do junction box.
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Old 04-24-2019, 09:08 PM   #11
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Re: If it's 80 ft long wire (20amps) a considerable problem for voltage drop?


Quote:
Originally Posted by rockman413 View Post
So I'm having a 5volt voltage drop, I may end up at 115V, since most devices is made for 110V-120V, even I got this home run wires in my house up to 80 Feet, I'm still good because 115V is > 110V, am I correct?

So need to move the AC or do a subpanel, just do junction box.
By my calculations you will actually drop only 2.5V over 80 feet. You are fine.
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Old 04-24-2019, 10:48 PM   #12
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Re: If it's 80 ft long wire (20amps) a considerable problem for voltage drop?


Quote:
Originally Posted by rockman413 View Post
So I'm having a 5volt voltage drop, I may end up at 115V, since most devices is made for 110V-120V, even I got this home run wires in my house up to 80 Feet, I'm still good because 115V is > 110V, am I correct?

So need to move the AC or do a subpanel, just do junction box.

Sorry, I mean, So NO need to move the ac or do a subpanel, just do a junction box.
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Old 04-24-2019, 11:02 PM   #13
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Re: If it's 80 ft long wire (20amps) a considerable problem for voltage drop?


Quote:
Originally Posted by Sdiver2489 View Post
By my calculations you will actually drop only 2.5V over 80 feet. You are fine.
Why your calculation is very different from KPD's (see the 2nd or 3rd post)
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Old 04-25-2019, 07:25 AM   #14
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Re: If it's 80 ft long wire (20amps) a considerable problem for voltage drop?


Quote:
Originally Posted by rockman413 View Post
Why your calculation is very different from KPD's (see the 2nd or 3rd post)
You're getting a few answers, but to properly advise you, we need the details.

Is this a 80' run to an AC unit? Most likely 240V
To do the voltage drop, we need the voltage and current of the AC unit.

If you are just running general purpose receptacles, then what @CodeMatters said will be fine.
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Old 04-25-2019, 08:49 AM   #15
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Re: If it's 80 ft long wire (20amps) a considerable problem for voltage drop?


Southwire has a calculator that when I ran it for 80 feet delivering 20 amps said you need 10 awg.
Site:
https://www.southwire.com/calculator-vdrop
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