No, what that means is that the furnace draws 7 amps of current when it is running. Current is the measure of the rate of flow of an electrical charge through a circuit. One ampere of current means that one coulomb of charge is flowing through the circuit every second. If the furnace is running for one second, it will be drawing 7 amps during that second. If the furnace is running for one hour, maybe you better get it fixed, but it is still drawing 7 amps while it is running. The current that the furnace draws is actually a measure of how well the furnace "allows" (or conversely, "resists") the flow of charge. According to Ohm's Law, current = voltage/resistance, so if you get a short circuit, there is theoretically infinite current (but not really, since there is always resistance in the wires). Excessive current can cause wiring and electrical components that are not designed for that level of current to fail, and even lead to a fire, which is why there are fuses and circuit breakers.
By the way, current can be measured by an instrument called an ammeter, which is placed in series with the circuit being measured. The instrument measures current by measuring the voltage drop across a fixed resistance.
Gary Shapiro, 2011 Georgetown 29' Class A
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