Question

An electrician must decide between 3 heaters. The wire that she is using is rated 15A maximum, anything beyond that is a fire hazard. Two of the heaters operate off a standard 120V circuit. One is rated 900W and the other 1800W. The third operates off a 240V circuit and can deliver 3000W of power. Calculate the amount of current for each.

Answer 1

Use the formula:
`P=IV`, where P is power (watts), I is current (amperes) and V is potential difference (volts).

For the first heater:

`900W = I_(1)*120V`

`I_(1) = 7.5A`


For the second heater:

`1800W = I_(2)*120V`

`I_(2) = 15A`


For the third heater:

`3000W = I_(3)*240V`

`I_(3) = 12.5A`