electricalperson said:
if half his house works then he might of lost a phase. an open neutral will make the whole house not work if im not mistaken.
Depends on where the lost neutral is. Someone here on the forum has a good power point on the subject. But if there is a cut or resistive neutral in a panel, or main, or even out on the service drop all of the loads on the phases will then be in series with eachother. This then shifts the balance (depending on load) of the potential at each load. For instance you have a single phase residence 240/120. The neutral is cut the load is in series at 240 instead of paralel and you have a steady load of 100w on each phase - you would not notice the difference. But if you change the load so that there is less on one, more on the other, the voltage seen on one phase will be higher - the other lower. A 197 volt light bulb may just be REALLY BRIGHT. A 197 volts across a power supply for say a television can burst into flames. The other phase would have 43 volts...
In this case, you could have nothing in half the house 'seem' to work, then turn on the 240 dryer or oven and balance the load much more equally - but not fully. And get for instance 130, and 110.... Everything 'seems' to work normal again....
If you were only getting whats left of only one phase (A) throught the load to back feed the other (B), you would have 120 on (A), and only whats left on (B). Depending on the kw of the dryer - much less than 120 nominal. Not enough IMO to make it seem as if it were working OK.