Greetings. I have a malfunctioning wall oven that I want to replace. I have done simple wiring in that past (mostly light fixtures), but have not ever wired a 240 V appliance before. My line coming into the wall consists of two 120V hots, 1 neutral, and 1 ground. The wiring is aluminum (all the 120V circuits in my house I've seen so far are copper). The current oven is wired with the two 120V hot oven lines connected to the two 120V wall leads (black wiring). The existing oven's neutral AND ground are twisted together and connected to the wall's neutral (white wiring). I found this to be curious given that there is a ground wire available in the wall. I believe this approach was permissible and maybe the last installer just got lazy. Based on some research I've done to this point, I've determined that I need to take extra care when wiring copper and aluminum together, making sure to add anti-corrosion material to the wiring and using a special Al Cu wire nut. There are however two concerns I have that I would like a little advice on. (1) I'm a little nervous that the last installer ignored the ground wire in the wall and might have done this intentionally because maybe the ground really isn't grounded. I have a finished basement and so I really can't trace any wiring. Most likely the last installer was lazy, but I want to make sure that the ground I see in the wall really is grounded. How would I go about to test that? (2) The replacement oven instructions indicate that: [I]models rated from 7.3 to 9.6 kW at 240 volts (5.5 to 7.2 kW at 208 volts) require a separate 40-ampere circuit. Models rated at 7.2 kW and below at 240 volts (5.4 kW and below at 208 volts) require a separate 30-ampere circuit. [/I]The wattage rating for the replacement oven indicates that I will need a 30 amp circuit. When I look at my current oven circuit breaker, I see that the breaker switch is at 40 amps. Given that the current oven has been running for years on a 40 amp breaker, I believe the circuit itself is safe for 40 amps (I regret that I did not write down the wire gauge when I last had the existing oven pulled out to take a look at the wiring - the next time I do this I will note the gauge and verify it is safe for 40 amps). Assumming the circuit itself is OK at 40 amps, what are the consequences of keeping a 40 amp circuit breaker when the oven is expecting a "30-ampere circuit?" Will replacing the 40 amp breaker with a 30 amp breaker be necessary? I have never replaced a circuit breaker before. Is this a job for a professional? I appreciate any advice given. If there is something else I should keep in mind, please let me know.

I have a lighting fixture, which was hooked up to a dimmer switch. Whenever you turn the dimmer switch on and to full, it would not light up. This used to work. I dont know how long this has not been working for and the tenant has moved out of the place as well. I took the light fixture out, and connected a multi-meter to it, one end to the black wire and one to the white wire. I was expecting to see 120V (or close to it) when I turned on the dimmer, but what I get is 18.1V instead. That doesn't sound right to me, so I took out the dimmer switch, disconnected it, and put the multimeter between the black and white wires of the cable coming out of the wall, and that only showed 46-47V. I would have expected that to be 120V as well. This is in the dinning room and the light fixture in the kitchen, which is next to the dinning room and I think on the same breaker, is also showing the same signs. How do I debug this problem and find out why I'm getting low-voltage ?