fuse box breaker not tripping when overloaded

[Judd Campbell]

I have a tenant that told me one of their bedrooms was having the power go out only to flicker back on after 10 min and then be totally back after 15 min.  they were running the lights, a tv, and a space heater (1500 watts marked on it!)

My concern is that the breaker did not trip on the fuse panel.  I think the wires overheated and only when they cool does the power come back on. 

I replaced the breaker for that circuit and found one outlet in that bedroom that had half an outlet not getting power.  I swapped that out with a new one too.  I changed the lightbulbs to CFL 12 watt units

The tenant put the heater back in the room and said the same thing happened. power went out only to come back on slowly and without tripping the breaker.  I have asked her to run the space heater off the bathroom circuit as it is a 20 amp instead of 15. 

Thoughts on where I should go from here? she said they have used that heater in there the last three years without issue. 

[Kyle Hipp]

it is probably not overloading the circuit, just overheating a connection so it wouldn't cause the breaker of blow. You could test resistance but I imagine it would only show when it is overheated.