Voltage Drop

[jstrang]

We have a 20 amp run that is 135 feet from the panel. Now we are going to pull # 10 thhn to the first jbox now from that jbox can we pull # 12 to the remanding boxes.The rest of the pulls are less than 80'?

 

[cpal]

We have a 20 amp run that is 135 feet from the panel. Now we are going to pull # 10 thhn to the first jbox now from that jbox can we pull # 12 to the remanding boxes.The rest of the pulls are less than 80'?

What is the circuit voltage and the anticipated load current. Is it a inductive load subjected to inrush??

How well do you want it engineered??, and volatage drop is not enforcable. It is a FPN reference

 

[jstrang]

it is 120/208 4 lighting no it is not subjected to inrush

 

[acrwc10]

it is 120/208 4 lighting no it is not subjected to inrush

Whats the load?

 

[charlie b]

Since the breaker is 20 amps, you can use #12 wire anywhere along the circuit you like. Pulling #10 to the first box, and #12 the rest of the way, is certainly allowable. Whether that is enough to resolve any voltage drop concerns is a matter of calculation.

 

[Hameedulla-Ekhlas]

We have a 20 amp run that is 135 feet from the panel. Now we are going to pull # 10 thhn to the first jbox now from that jbox can we pull # 12 to the remanding boxes.The rest of the pulls are less than 80'?

It is okay and take care of voltage drop too.

 

[bob]

We have a 20 amp run that is 135 feet from the panel. Now we are going to pull # 10 thhn to the first jbox now from that jbox can we pull # 12 to the remanding boxes.The rest of the pulls are less than 80'?

Can't answer the question because you did not indicate the voltage or the load .

 

[brian john]

Assuming 16 amps 55' to first JB

Voltage at the first JB

Estimated Drop 2.1 Volts
Load At Circuit End 117.9 Volts (based on 120 VAC)
Voltage Drop 1.8 Percentage

http://www.csgnetwork.com/voltagedropcalc.html

 

[Smart $]

We have a 20 amp run that is 135 feet from the panel. Now we are going to pull # 10 thhn to the first jbox now from that jbox can we pull # 12 to the remanding boxes.The rest of the pulls are less than 80'?

If 135' is the total length of the run, how far to the first jbox with #10?

120 ***OR*** 208 volt lighting?

• Do loads (luminaires) get connected as the circuit proceeds with #12? I can't imagine a 20A circuit for one luminaire.
• So how are the fixtures laid out and what is the distance from the first jbox?
• Are there branch #12 runs to fixtures, or are the fixtures connected sequentially along a single #12 run?
• What is the total number of fixtures, and the load value of and distance wire-wise between each fixture?
• This is a two-wire branch circuit?

All these and potentially other factors play a role in voltage drop.