mjenson

I bought a 1600sf house built in 1970 a ranch w/basement converted to an apartment. And decided to map the breaker box and found all the upstairs lights & outlets (except -dryer and a bathroom ceiling heater). And all the downstairs lights and outlet (except kitchen outlets) are on 2- tied together 40amp breakers. They are in position 11&12 in the breaker box. If I flip these almost all of the house goes out. But I also have a combination of 15amp & 20amp breakers that will turn off different sections of the house when the two 40amp are on. Is this a common way they wire a house? Is there any thing I should know before I tie in to the 15 & 20amp breakers to add can lights other than their 80% capacity?

Ben8n

You need to call a electrician to get this fixed.
The reason comes down to a matter of saftey.
If you were in your bathroom blow drying your hair or something it would take 40 amps of power to trip the circuit meaning you would be long dead. It takes roughly .66 of 1 amp to kill someone. That is why it is important to properly place outlets to breakers. GFCI's need to be installed in bathrooms and arcfault breakers in the bedrooms. You will most likely need the house rewired though to fix this problem BUT... Your saftey should be your number one concern.

JoeD

It could be fine. You could have a split bus panel. The 40 amp breaker in the top half of the panel supplies power to the lower half of the panel where all the normal 15 & 20 amp breakers control the individual circuits. If the 15 & 20 amp breakers turn off the receptacles and lights in the house then you are probably fine.

mjenson

The 15 & 20 amp do turn off the receptacles and lights. Should I still figure 80% of the two 40 amp breakers which I assume is 80 amp since they are tied together and see if all the draw on 15 & 20 amp = 80% or less? It seems logical but is it necessary since every thing is not on all at once. I don't generally blow any breakers.

I do have a couple open spaces in the box. I suppose it would be safer to run any new can light straight from the box instead of tying in to another breaker.

JoeD

If the receptacles & lights are only turned off by the 40 amp double pole then this is very bad. Is it possible there is a sub panel somewhere that this double pole breaker turns off?

kok328

What guage wire is connected to the 40amp, 2-pole breaker?

mjenson

To clarify, the two 40 amp that are tied together turn off most of the house but when they are on there are other 15 & 20 amp breakers that turn off different areas that are controlled by the two 40 amp.

I'm not sure of the wire size coming out of the two 40 amp. I see other wires that say 4 AWG and it seem to be a little larger than that. But I see that the wires coming out of the two 40 amp go behind the breakers and appear to be very short. Un-like all the 15 & 20 and the one 50 amp which all go out the top of the box into the attic.

I do have another breaker box next to this one that has one large main switch but I have never checked to see if it turns of every thing I assume it does. I will check once it is convenient for every one in the house. It may just turn of this box. This box has larger amp breakers 30's & 50's for water heater, range, hot tub-(no longer connected).

kok328

"that are controlled by the two 40 amp"

Sounds like a sub-panel to me, especially if you have another box next to this one.

If that's the case then your fine.

JoeD

Are there any parts of the house that ONLY go off with the 40 amp breaker? If the answer is yes then you have a problem.