100 amp wire size chart. Tldr to feed a 100 ampere secondary panel 200 ft. Usually a general purpose house circuit is designed for 20. The national electrical code nec recommends a maximum voltage drop of 3 percent for individual household circuits known as branch circuitsthis is a good goal to shoot for when sizing the conductors for an underground cablethe following are the maximum lengths of cable you can use while still maintaining a 3 percent voltage drop for the given wire size awg and circuit voltage. The number and type of electrical devices connected to a circuit determine the ampacity requirement of the conductor.
Looking for the right size wire for your 100 amp sub panel for a detached building garage or shed. When determining feeder conductor size youll want to consider the lowest temperature rating of any connected termination conductor or device as per national electrical code nec article 11014cwhile the cablewire may be rated at 900c youll likely find that the terminals are rated at 750c or not labeled at all. 11014c1a tells us that since were working with 100 amperes. Current is measured in amperes or amps.
4 the nec allows a maximum of a 3 voltage drop on the main branch of a circuit at the farthest outlet of power and 5 total to both feeders and branch circuits to the farthest outlet. 628 volts is less than 3 of 240 volts so i found the size conductors to use. This means that a 100 foot long run of 14 awg wire carrying 125a would still have an acceptable voltage drop. Each wire should be 2 gauge in size.
Wire is sized by the american wire gauge awg system. When it comes to the lines connecting master and secondary panels where the line will carry as much as a full 100 amps use a 2 gauge non metallic sheathed electrical cable. The calculator allows entry of a voltage drop but caution should be used when doing so to make sure you are calculating the wire sizes in accordance with nec article 210 19 fpn no. For 100 feet the voltage drop would be one tenth as much or 3125v.
You must use the correct size wire for the current load requirement of the circuit to prevent the wire from overheating. Wire gauge refers the physical size of the wire rated with a numerical designation that runs opposite to the diameter of the conductorsin other words the smaller the wire gauge number the larger the wire diameter. The wire size chart below shows allowable ampacities of insulated conductors rated up to and including 2000 volts 600c through 900c 1400f through 1940f not more than three current carrying conductors in raceway cable or earth directly buried based on ambient air temperature of 300c 860f. Common sizes include 14 12 10 8 6 and 2 gauge wire.