Troubleshooting Common Electrical Problems:
New Electric Heater Blew the Fuse

By Terry Peterman, the Internet Electrician

Q.  I recently bought an electric heater and it blew my fuse in the basement.

My electrical outlets on the main level, now,  no longer work along one side of my wall. 

I pressed a reset button and it still does not work.

A:  The electric heater that you purchased is likely of high enough wattage that it should be on its own dedicated circuit. 

The largest electric heater that you should attempt to use on a 120V dedicated circuit is something under 1500 Watts. (1500W/120V = 12.5A)

You should only knowingly load a 15A circuit to 80% of it's capacity (80% of 15A is 12A). 

Given that this existing circuit has several outlets on it now, the largest electric heater you should attempt to use is 1000W or less (depending on what other loads are frequently used on this same circuit).

The outlet that you plugged the heater into must be a GFCI (ground fault circuit interrupter) protected outlet. 

Pressing the reset on this receptacle will have no effect because it is likely that the outlet didn't trip, the breaker (or fuse in older homes) is what tripped. 

GFCI protected circuits will trip on a ground fault condition.  Circuit breakers trip on an overload condition (high current or short circuit). 

What to Do

• Go to your electrical service panel and you should find a breaker that is in the tripped position (usually somewhere between the 'off' and the 'on').

• Push the suspect breaker hard toward the 'off' position until you feel a 'click'. 

• Then return the breaker to the 'on' position (with the heater now unplugged! and you should restore power to your circuit. 

• Now go push the 'test' button on the GFCI outlet and it should trip with an audible 'click'.  Push reset and that outlet should be working again. 

This test procedure for GFCI outlets should be performed once a month by manufacturers' recommendations.

- Terry Peterman, Internet Electrician