As per my knowledge, the overload current will trip a circuit breaker and will burn the fuse of any fused switch. How come when my main breaker failed (because of the steamer I reckon because it happens every time we use it) the fuse of the switch that held steamer socket + the ELCB didn't trip (It jumped directly to the MCB)?
Electrical – Why did the main circuit breaker trip before the branch circuit breaker
electrical distributionelectrical-panel
Related Solutions
The two branch circuit breakers will trip if the load on their protected circuit is greater than 32 amperes, and 25 amperes respectively. However, since the main breaker trips at 40 amperes. If both branch circuits are pulling a full load the branch circuit breakers will not trip, but the combination of the loads will trip the main breaker (32 + 25 = 57 > 40 as you have said).
It's a very common situation to have the branch circuit breakers total more than the main breaker, but this is almost never a problem since the circuits usually don't pull a full load. Remember, circuit breakers are there to protect the wires. They shut off the power if you are drawing enough power to damage the wire, so installing a larger main breaker is likely not an option (unless you contact your power company and have the service upgraded, which will include upgrading the feeder cable).
Contact your local power company, and speak to them about a service upgrade. Other than plugging less stuff in, or cycling loads, there is not much you can do yourself in this situation.
Mike Holt's forum, discussing what breakers will fit in that box.
doityourself.com, CasualJoe:
If you remove one and inspect the bus, you'll see the attachment portion of the bus for the THQP breakers is perpendicular to the main stabs that the type THQL breakers attach to. THQP breakers snap around the bus where the full sized THQL breakers fit tightly over the bus. This is obvious if you inspect the breakers and bus carefully. If you remove enough breakers, you'll see the difference in the bus in the areas that the full size THQL breakers MUST be used and won't accept the thin breakers. At this point, you'll have to use your head to determine which spaces will accept the thin breakers. The only other recommendation I could make would be to go to a supply house that stocks GE load-centers and ask them to explain it to you and show you the difference.
The breakers with the green labels look the newest, take one of these to the store with you and make sure it matches the mounting. I'd call it an 8 slot panel, using tandem breakers to make 12 branch circuits (otherwise there'd be only be 6) and one (2 pole) main. In your panel, it would have been borderline acceptable to take the cover off, say "ewww" and put it back on, having TOUCHED NOTHING. Now that you have went in there and played with stuff, I'd be concerned that you have loosened the connections of the wires and/or the buss-bar contact clips of the 50yo breakers. If you're going to continue onwards with that panel, consider getting those leads away from the neutral bar, shortening them while you're at it. At least check ALL of the connections. Upgrade that panel, please (or KEEP OUT). I don't want to see this in your next post:
Related Topic
- Electrical – Fuses blow and sparks appear when using the home’s wiring circuits
- Electrical – Problems with common lead bad connection at meter
- Electrical – Burnt modules but no breaker trip
- Electrical – Why does main breaker trips before the smaller one
- Electrical – Breaker tripped under no load
- Electrical – How did the ground and neutral become energized by a short in the buried main line
- Electrical – Main breaker and branch breaker tripped simultaneously
Best Answer
"Circuit breaker coordination" is the term used when setting up multiple breakers / fuses. The trip curves overlap and in many cases a small breaker can take longer to trip than a large breaker.
One example I can provide is this: the plant I work in was not built with the same brand breakers. In one area an 800 amp main will trip out prior to the 400 amp mcc feeder or the 100 amp breaker on the motor overload bucket. The cost to coordinate these breakers to the correct ones would be several thousand dollars and it happens so infrequently that the owner is OK with the occasional down time. By comparing the curves of the different types of breakers you can see that fuses and small inverse time breakers will hold at 4-6 times their rated value for a short time.
So depending on the loading of the circuit and type of breakers used, if not well coordinated, the main will open before a much smaller breaker protecting the wiring but dropping power to everything. A well coordinated system takes planning and the correct breakers and fuses to prevent this from happening.