What size wire should I run to service 80amps to a barn? Run is about 125 feet to panel box.?

Question

What size wire should I run to service 80amps to a barn? Run is about 125 feet to panel box.?

Answer 1

It does not matter if you use 10% or 80% of the rated load ... the calculation is the same! What does matter is the ratings on the equipment you install(i.e. breakers, wire, etc) Most items are rated at 75 Degrees C , but if not,  you have to derate the circuit. With that being said.... if you are running 240Volts to the barn you are allowed a 7.2 volt drop, if you are running 120 Volts, then you are only allowed a 3.6 volt drop to fall within the 3% standard. If you run 240V then you are allowed to use #4 AWG, if it is 120V then you need to use #1 AWG. If all of your equipment is not rated at 75Degrees C or higher.... then you will need #3AWG for 240V and still a #1AWG for 120V. Hope this wasn't too confusing. If you have questions, feel free to email me.

Answer 2

It depends on what you are doing, the type of load and the amount of use. Is this a 80 amp steady load or a 80 amp breaker feeding a lower load?   #4 THWN  is rated at 85 amps, this does not allow for length of run.  If you are running heaters or lights that are on all of the time, the size is too small. This is for copper in a raceway of no more than 3 insulated conductors.   Your best solution is to call a qualified professional electrician.

Answer 3

that long a run I would Say no less the 2/0

Answer 4

#3 Cu in pvc assuming 2 ungrounded 1 grounded and 1 equipment grounding conductor(s) #4 Cu direct burial.  If you are adding 80 amp sub to your barn I would suggest doing a load calculation on your service.  Call a Pro, at least get an estimate at the very least you will learn some new terminologies and have someone to call if you s***w up