The maximum current for circuits using 12 gauge wire is 20 amps, according to US electrical regulations. 14 gauge has 30 amp ratings and higher gauges have even higher current limits.
Electrical wiring rules vary by country but the vast majority of countries require some form of certification or licensing before they will allow you to work on their electrical systems. The license usually requires some form of training as well. In most countries, it's illegal to work on an electrical system without a license.
In Canada, electrical wiring rules are controlled by two organizations: the Electrical Safety Authority and the Canadian Electro-Technical Institute (AIT). The Electrical Safety Authority regulates electric heaters, air conditioners, and other appliances that use electricity to heat water or air. These include space heaters, water heaters, and air conditioners. The Canadian Electro-Technical Institute controls professional engineering practices and provides certification programs for those seeking to become licensed electrical contractors. There are three levels of certification available from AIT: Certified Installer, Professional Technician, and Senior Professional Technician.
In the United States, electrical wiring rules are controlled by two organizations: the International Electrotechnical Commission (IEC) and the National Electric Code (NEC).
The next grade up is 12-gauge wire, which can carry up to 20 amps. As a result, the amp rating of a circuit breaker has the following relationship to the wire size: A 20-amp breaker should never be used on a circuit with 14-gauge wires (anywhere on the circuit). A 16-amp breaker would be suitable for that job.
The voltage drop across each conductor of a dual-voltage system must not exceed 15 percent in order to meet code requirements. This means that if you're using only red wires, for example, then the total voltage drop across those wires cannot be greater than 15 percent of 120 volts or 18 volts. If black wires are also present on the circuit, the maximum voltage drop across all three conductors cannot be more than 30 volts.
Since the amperage rating of a circuit breaker does not change regardless of what size wire is used in the circuit, it's easy to see why it's important to use a breaker capable of handling the load you plan to put on the circuit. For example, if you want to install a air conditioner and plan to use 20-ampere circuits throughout the house, then you should select a breaker that can handle 20 amps. Otherwise, you might open the circuit too soon because a lesser breaker could have been adequate had you known how much current was going through it.
The maximum current (amps) across a 12V circuit is proportional to the wire size (AWG) and length.
|American Wire Gauge (#AWG)|
|Length (feet)||Maximum Current (amps)|
The ampacity of an electrical wire is the greatest amount of current it can carry. The ampacity of a 12-gauge wire is larger than 20 A. As a result, the answer is "Yes."
A 20-ampere circuit requires two 10-amp circuits in parallel. If one circuit fails, the other will still provide sufficient power for the lamp until the problem is fixed. The fact that 12-gauge wire can handle more current than 20 A means it can safely carry the load if some of the wires break or conductors are missing from the cable run. 12-gauge wire is most often used to supply power to lamps and small appliances such as hair dryers and vacuum cleaners.
As you can see, 12-gauge wire is suitable for supplying considerable current into loads that require heavy duty wiring. Before you use any heavier gauge wire, however, be sure to check the wiring code in your area about how much current various sizes of wire can handle. For example, if the code limits the total current in a household circuit to 30 amperes, you should not use wire that can carry 40 amps or more because it could cause damage to your home office equipment and lead to fire hazards.
For example, if your breaker's amp capacity is 20 amps, you should only use 12-gauge wire; if it's 15 amps, the entire circuit should be 14-gauge. Electricity needs to flow through all the wires to reach its destination, so if one or more of the wires is too small, it will not provide enough a channel for current to travel down.
Using 14-gauge wire for a 120-volt circuit will help prevent overheating of the wiring due to less resistance in the wire. The amount of heat that can be absorbed by a copper wire depends on two factors: its diameter and its length. The smaller the diameter, the greater the heat loss (or radiation) when electricity flows through the wire. The longer the length of the wire, the greater the risk of it reaching excessive temperatures because more time is needed for heat to be lost or conducted away from the hot spot. For example, a 22-gauge wire used as a leg conductor in a bathtub fills with hot water in less than 5 minutes; if it were 24 or 26 gauge, it would take much longer because more room is required for the same amount of current.
The old rule of thumb was that you should always use at least twice the gauge of wire that transports 100 volts or less.
Max is the rule. For # 14 wire, a 15 amp breaker is required, a 20 amp breaker is required for # 12, and a 30 amp breaker is required for # 10. But these are maximum loads; in real life you'll never see them happening. For normal use, 8 feet of # 14 will run on a 15 amp breaker, 12 feet on a 20 amp one, 16 feet on a 30 amp one.
The actual load depends on how many appliances use each conductor. If they all share current, then it's better if they're equal. So if one appliance needs 10 amps while another needs 20, then you should space them out so that each uses about 10 amps. This works well if there are enough outlets to go around. If not, you might have to get more conductors installed or change some things around.
In any case, as long as you don't overload them then you're fine. A generator won't hurt anything even if you give it everything you've got because electricity isn't sent through copper but rather magnetic fields which aren't affected by motion. The only thing that could possibly be harmed is metal parts inside the generator itself if it's been built poorly. But since generators are always running on max output anyway, this shouldn't happen too often.