If a 100A breaker panel has five 15A breakers and four 20A breakers could this overload the panel?

already exists.

Would you like to merge this question into it?

already exists as an alternate of this question.

Would you like to make it the primary and merge this question into it?

exists and is an alternate of .

The short answer is "no". A 100A panel will be protected by a 100A or smaller main circuit breaker or fuse, and if the sum of all the loads on the various branches exceeds the main breaker rating, it will trip and power will be disconnected long before any damage can occur to the panel.

for USA, Canada and countries running a 60 Hz power supply service. The short answer is that safe capacity in buildings is determined by a load calculation, not by adding up the nominal ratings of breakers. A quick check for signs of overload would be to check the temperature of your 100A main breaker. Use a $50 non-contact thermometer from a hardware or home improvement store and look for the main to be significantly hotter than the average of other breakers -- over 100F or more than 5-10F hotter than other breakers could be cause for concern.

On a 100A-rated electrical service, you have 19,200 W of continuous power capacity to stay within the 80% of rating load limit indicated by National Electric Code. You can calculate about 3W per square foot of living space for convenience receptacles and lighting, and you should also subtract the wattage of each piece of permanently-installed equipment (such as a garage door opener, electric range, 240V water heater, etc.).

Just like any resource, anything could be abused. You typically do not use all of your electrical circuits at the same time. A 100A panel will usually also be the equipment for disconnecting from the utility service, and have a MAIN BREAKER service-disconnect that will trip (eventually) when you have exceeded safe home capacity. Each individual 15 or 20 amp circuit could also have an 'overload' plugged into them. Just as long as you don't turn on every device at the same time, the smaller circuit breakers won't blow and everything is fine.
Clarification: A 100 amp electrical panel is so called because it is rated at 100 amps. The main breaker or fuse is intended to disconnect power if the load exceeds 100 amps on either of the 2 "legs" of the service. The load on the panel is not the cumulative RATING of the nameplate current limits of the individual breakers in the panel. It is the actual load on the breakers that adds up to the load.
A 15 amp breaker is rated at fifteen amps, so that it will shut off if the current goes ABOVE 15 amps. This is to protect the circuit conductors from damage.
You could have 20 circuits with 15 amp breakers on each one and only have a load of 5 amps on the whole panel [not 300]! Remember there is no current if there is no load [load allows current]!
Do you get a speeding ticket because your speedometer goes up to 120 mph if you are going 25?


As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.

If you do this work yourself, always turn off the power
at the breaker box/fuse panel BEFORE you attempt to do any work AND
always use an electrician's test meter having metal-tipped probes
(not a simple proximity voltage indicator)
to insure the circuit is, in fact, de-energized.

170 people found this useful

Is it possible to overload a panel with too many duplex breakers?

YES. By duplex breaker, you mean 'tandem breaker', a special breaker designed to allow you to get more circuits into a panel that is full or almost full. You most likely hav

If the service panel you have 100A service can you install a 100A circuit breaker in the original panel to feed another 100A add-on panel?

DO NOT FOLLOW THE INSTRUCTIONS BELOW! According to this logic, one could chain an infinite number or sub-panels off of a single one hundred amp feed. The second law of ther

How many lights and outlets can go on 15A or 20A breakers?

Answer for USA, Canada and countries running a 60 Hz supply service. Lights Lights and outlets are normally wired on separate branch circuits, which means that the lights

How do you wire a breaker panel?

Answer . If you are adding a branch circuit, go to your local home improvement center and buy a book. It will tell you how to do the job legally and serve as a handy refe

Where do the 240 breakers go in panel?

A two pole, (220-240 volt) circuit breaker can go anywhere in a panel where it will physically fit, connecting to two poles on the buss bar. However, if you don't know this al

Can I install a 20A and a 15A single pole circuit breakers inside a sub-panel that has a 30A double pole main circuit breaker and 8-3 with ground cable feed coming from the main electrical panel?

Answer for USA, Canada and countries running a 60 Hz power supply service.. Yes you can add these two breakers to the sub panel. You will have to keep in mind the fact that i

How many outlets or lights can go on 15A or 20A breakers?

Building codes will vary. In the US, the National Electrical Code (NFPA 70) is the basis for most of those. The answer will vary depending on what the structure is. For a sing

If a 100A panel has 8 20A breakers and 8 15A breakers could this overload the panel?

The only time the panel will be overloaded is if every circuit breaker was loaded to maximum capacity. When these panels are designed, the main breaker protects the two bus ba

What to do with gaps in breaker panel?

That's why breaker panels are provided with knock-out blanks. You only remove the blanks that you need. If you have removed too many of the blanks, install unused breakers i

What is the formula the breakers in panel?

There is no formula used to fill a distribution panel. The panel is loaded according to the circuits that are to be connected to it. After you have determining what breakers a

Can you have a breaker panel in a bathroom?

absolutely not... Besides the fact that "absolutely not" is the common sense answer, the NEC strictly forbids electrical panels from being in bathrooms. There are very few o