DIY Manual

37 | P a g e 10-543-1 REV A
DIY Manual
WIRING & CIRCUIT PROTECTION
Wires are used as conductors of electric current. Insulators are material specifically designed not
to conduct electricity. When current (amps) flow through the wire, a certain amount of heat is
created due to friction caused by the wire’s natural resistance. The greater the amps flowing
through the wire, the greater the heat. Using an undersized wire to carry excess amps leads to
excessive heat, which leads to a breakdown of the insulation, which leads to failure of the wire
in terms of a short circuit or potentially a fire!
Circuit breakers are used to protect the wire in which the breaker is installed, not necessarily the
equipment or electronics at the end of the wire. If you use a #10 AWG wire to carry 30A of
current, then you need a 30A breaker. When 31 A (+/-) flows through the 30A breaker, the
breaker trips, thus protecting the wire from insulation breakdown. ALWAYS USE APPROPRIATE
CIRCUIT BREAKER PROTECTION!
Wire ampacity refers to the safe current carrying capacity of a wire. The National Electrical Code
(NEC) publishes charts showing wire ampacity limits. Refer to such a chart when selecting your
wire size. Selecting and installing the proper gauge wire ensures safety and system efficiency.
Know your system and its current draw, and always use the right size wire and the appropriately
rated circuit protection.
WIRE SIZE AND GAUGE
Wire size is called gauge and is often referenced to the American Wire Gauge (AWG) standard,
such as a #10 AWG wire. The higher the wire gauge number, the smaller in physical size is the
wire. For example, an #18 AWG wire is smaller in physical size than a #10 AWG wire.
Figure 1
DETERMINING WIRE GAUGE