When you turn on lets say your microwave lights in the back side of your house go dim then go completely off sometimes coming back on on there own things is none of the circuit breakers are tripped?

Answer 1

In this case I would assume that your power lines are At Fault, or your protection (the breakers) is not adequate for the job (too big values for tripping). This problem is a little complex.

You see, every cable running through your walls (and extension cords) is rated at a certain power level (or, rather, by amps at the rated voltage). That has to do with how many electrons (or whatever is used to transport charge in your power lines) are free to "do the job" and with the heat dissipation of the said wire - and that is directly related to the wire's diameter and materials used to construct it. Both of these properties end up having a great influence on the power rating.

If you try to "pump" more power through a conductor (a cable) that wasn't rated for it, two things will happen:

a) the equipment connected to it will experience "brownouts" (voltage drops, but not dropping completely - just 'enough')

b) the conductor (cable) will heat up greatly, even to the point of melting(!)

The brownout problem is mainly caused by heat lossess (heat increase is roughly proportional to resistance increase, so more heat means more power lost in transmission). But this heat is a significant fire hazard as well!

This usually happens when you try to connect too many devices to one outlet, or too powerful devices where they shouldn't go. This is a hazard in many ways and should be avoided as much as possible. Especially so in TN-C installations, where the 'ground' wire joins up with the 'neutral' wire! The ground wire is designed to remove unwanted (dangerous) voltages from metal cases of devices -- if the neutral wire fails first (by burning out), there is a high risk that the voltage will find a return-path through the metal case of the device (!), becoming a significant shock hazard to the unwary operator.

As for the circuit breakers, the most probable cause for them not tripping is that they're overrated for your electrical installation, and as such, they will NOT protect your installation from melting or catching fire. Why is this so? Well, as it should be clear by now, the circuit breakers' rating should match the power rating of your installation - this is one of the cases where "more" doesn't mean "better". If they're underrated, they will break for "aparently no reason" because they will allow less current than your installation can handle; if they're overrated, on the other hand, the wires in the walls (or in devices) will heat up much faster and will probably fail before the current running through them even approaches the breaker's trip rating, because the breaker will allow more current than your installation can handle. This matching should be performed by at least someone who knows the exact details of your home's electrical grid, and ideally by a qualified electrician/electrical engineer.