Wrong amperage breaker

My son bought a house in Orlando, FL built in 1987. I have sorted out all the electrical abnormalities except for one last thing last thing.

It's clear someone added an additional breaker to the panel to run an extra circuit to put four extra outlets in the garage. What smorgasbord of elements!!! First, there are no GFCI's anywhere. They ran 12-2 cable (w/ground) to a junction box and then "T"ed it with a cable running to one wall and another cable running to the other. One cable is 12-2 as you'd expect but the other is 14-2. What??? All receptacles are 15 amp. instead of 20 as you'd expect with 12-2 wire. And to top it off, they used a 30 amp breaker versus a 15or 20 amp. What were they thinking? More is better?

My intent is to put a 20 amp rated GFCI on each wall ahead of the other downstream receptacle and change each of them to a 20 amp rated ones. Of course I'll change out that 14-2 feeder wire to 12-2 so it's all the same. And I'll change the breaker to a 20 amp as it should be.

My question is, this work was likely done maybe a decade or two ago. I realize it all depended on what was plugged in, but with the use of a section of 14-2 and the 30 amp breaker, is it a wonder there was never a fire at some point? Just curious. Thank you.

 

As long as you are passing through the receptacles, you can use 15 amp receptacles on a 20 amp circuit. I would install a 20 amp GFCI breaker, and change the 14-2 to 12-2. Your assumptions are correct. Basically the wiring itself became your overcurrent protection device, since it was rated less than the breaker. It could have caused problems if overloaded to the extent the breaker wouldn't trip.

 

To find even one 20 amp duplex receptacle in a house would be strange to me. Chandler is correct, the 15 amp devices meet code and always have and are rated for 20 amp feed-through for use on 20 amp circuits. Stop and think about it, what typical home appliances have a 20 amp rated plug on them? None I can think of.

The only thing that surprises me is the 14-2 cable being on a 20 amp circuit and the breaker being increased to 30 amps. This was likely done after the house was built and was done without a permit or inspection.

 

In addition, the reason I suggested the GFCI breaker, is it appears, from your description, the receptacles are spidered from a junction box, making them not "fed through" technically, although they are fine in your situation. The GFCI receptacle must be installed in the first instance receptacle box, and the remaining run off the LOAD side of the GFCI. With the GFCI breaker, you cover all your bases at once.

 

That was a good observation on the 15 amp receptacles. Typical 20 amp kitchen circuits always have regular outlets. This garage circuit just struck me as odd. Whoever installed that wiring seemed to be of a confused mind and unaware of how to safely achieve the goal of a heavy duty circuit. Too heavy a breaker, one section of cable too light, one section of cable just right, and the receptacles probably okay unless a real heavy duty item with a dedicated 20 amp. plug was going to be used.

I kept thinking of the phrase I have seen so often in this forum: "Safe wiring is not something to be learned after the fire trucks have left." It is better to ask questions if you are not sure. This forum is a blessing.

 

And Mr. A would have a different comment on the 20 amp receptacles then us south of the boarder. Canada requires them IIRC.