Circuit Mystery

[LCHIEN]

I was working in the garage and it was chilly so I put on the electric space heater - 1500 Watts, The Outlet I used was for utility and It is shared with the overhead lighting sockets. MY fault, I guess I added the ceiling outlets for the lighting many years ago, but I surprised with the breaker tripped after about an hour of this. Now yes, the heater was drawing 1500 watts and the lights were drawing about 300 Watt (7 40W shop lights), but I've done it before a few times and never had any trouble on this 20 A line (2400 watts and I was drawing about 1800 W after the heater cycled on..

Bang the lights go out.. and I know right away the breaker tripped. So I cussed and reset it and left the heater off. About 3 minutes later the wife comes in and says Bad News, the Microwave oven just broke. Now its 15 years old and maybe not unexpected but its too coincidental. I say the breaker just tripped and I reset it so see if its working again and sure enough it was. So this is the second microwave we have in the utility room just off the kitchen near the middle of the house. And the microwave is in a nook where that's supposed to be for an upright freezer.


Now that means the guys that wired this house 30 years ago wired the freezer outlet to the Garage light circuit which was probably also connected to the two outlets originally in the garage. How does that make any sense?

So if she uses the microwave (1400 watts operating) then I have some issues in the garage on that utility circuit, at least if I want to use the heater.. But I guess this is the first time I noticed this in 17 years.

[dbhost]

And that sir is exactly why I had a dedicated sub panel run to the garage workshop.... I had lighting circuit that is shared with the front hallway, including the socket my wife plugs the vacuum in. So you see things could get overloaded, dark, and dangerous very quickly...

[twistsol]

If you're a builder's electrician paid by the job, you're trying to get in and out as quickly as possible. The garage probably had 1 or 2 light bulbs for lighting and required an outlet by code. Running those from the closest circuit that wasn't fully loaded was fastest and cheapest.

May daughter's house in South Dakota built 6 years ago had an outlet in the garage that was tied to the GFCI in the kids' bathroom. The GFCI tripped, and only their three year old daughter noticed it because the bathroom night light didn't work. The food in the freezer in the garage spoiled.

Our house, built in 2020 has all the outdoor outlets tied to a GFCI in the utility room which also provides power for the electronics to the gas water heater and the air exchanger. In a rain/snow storm, the Christmas lights tripped the GFCI when the timer kicked on and we had no hot water in the morning.

[capncarl]

Sounds like typical “Builder Grade” contracting to me! Makes you glad that there wasn’t a freezer involved! The electrician that wired my house connected the receptacles on our back porch glass room and patio to the gfci receptical on the front porch. There can be all matter of stuff plugged in on a patio and glass room and when it tripped a breaker during a cookout it was a real circus trying to find where this critter was hid!

[Jim Frye]

Oh yeah, I have a similar issue in my 6 year old home. When I built my basement shop, I ran two 20 amp., 12 ga. circuits from the main panel to the shop. One for the lights and ambient air filter, and the exhaust fan, and one for the outlets in the shop. Since I never run more than one tool and the shop vac on the outlets, I figured all was good. I sometimes run a 1500 watt heater in the shop when finishing, so all is good. Then SWMBO wanted a central vacuum system, so I installed the power unit in a central location in the basement and since the unit was to be located on the outside wall of the shop, I "conveniently" ran wires from a shop outlet up the wall to a new outlet up by the sweeper. The sweeper draws 15 amps. and the power head draws 2 amps., so all was good. Good until one day I was curing a varnish finish in the shop with the heater on and I started sweeping the main floor. "Boom, Boom Out Go The Lights".

[LCHIEN]

I can understand they sometimes do some wild routing to save a GFCI, like powder room and outside outlets on the same circuit. I guess at one time GFCI were expensive, over $20 and copper was relatively less expensive than it is today.

But I don't think there's a GFCI involved, even though there's an outlet in the utility room which has water outlets for the washer.

[Jim Frye]

The local code here is pretty stringent on GFCIs. All bathroom outlets must be GFCIs, as well as all exterior outlets. Garage circuits must have one as the first in the run. All basement outlet circuits must be have a GFCI as the first one on the run. Kitchen countertops must have at least 50% of the outlets as GFCIs protecting one non-GFCI outlet, including islands. All outlets in a laundry room are to be GFCIs even if a washer and/or dryer isn't plugged into it.

[LCHIEN]

Well, that is the current code. This house was built to codes that applied in 1992. that appear to require them in bathrooms and outdoor outlets.
AFIK the garage does not have a GFCI in the original circuits that supply the two original outlets.
There are four GFCI... one in the master bath, one each in the upstairs baths, one in the powder room downstairs that also controls the front yard outlet and I'm guessing the back yard outlet. I do not know that any of the utility/laundry room or kitchen outlets are GFCI protected.
Todays codes appear to include breaker box combination AFCI/GFCI/breaker components for all circuits.

[cwsmith]

A couple of decades ago I rewired (or re-circuited) our house in Painted Post (sold last August). Putting in a new service and breaker panel, the wire and outlets were updated and in the process every circuit and outlet was checked and on the back of each cover plate I marked the circuit breaker number, including the light switches. It's good to know exactly which CB it feeds whatever outlet, switch, etc.

After buying the house here in Binghamton in early summer, I decided to check out the wiring well before we moved in and found a few oddities in the process. like shared commons between boxes, ungrounded outlets, etc. I had one switch in the side entry way that didn't seem to do anything. During the day I was checking everything and it just seemed like a dead switch, not turning on anything when I flipped it. The wiring went back into the wall and I couldn't find where it went. Every other switch in the house activated either a light or a wall outlet that would activate a light if one was plugged into it. A lot of the wiring was old and I replaced it as needed. But most of the wiring was relatively up-to-date for an old 1887-built home. We had just had the service upgraded, removing the old fuse box and installing a new 200 amp panel. I asked the licensed electrical contractor about it and he said he'd checked everything, found the same thing, but just decided to leave it alone as it was harming anything.

We had also had the kitchen remodeld with new cabinets, new ceiling lighting fixtures and some relocation of the stove, frig, etc, with the old ceiling fan removed and overhead lights installed on that circuit. Still couldn't find what that entry hall switch was for.

So we moved in near the end of summer, winter soon arrived and of course days got darker a lot earlier, especially when we went back to standard time. One early evening, we came home from shopping, walked into the kitchen and flipped the switch to turn on the kitchen lights... NOTHING. I checked the new panel in the basement and nothing was tripped. I checked the new florescent ceiling fixtures and there was no current. Re-checked the switch circuits and they were dead also. So, electricity to the ceiling lighting in the kitchen, and the circuit was dead, but the panel CB was on with nothing tripped. We ate by candle-light that night!

I called the electrician, explained what I found and he came the next day. Ater an hour or som he found nothing wrong and told me that it would be expensive if he spent the day probing the walls and suggested that since I appeared knowledgeable, I save a lot of money doing my own exploring, because nothing was obvious.. We even called the contractor who had installed the cabinets did the new dry wall, etc. He said he didn't recall anything, but he did come over and discussed the project with the electrician and me..

I checked everything that I could think of over the next day or so and we had our supper by candle-light for two more nights.

At that point, I figured just maybe the switch was bad, but it didn't appear to be; the wires were properly attached and there was no visible sign of failure.

So, the next morning I decided to play with an electrical wiring simulator program I had, and happened on the idea that perhaps that 'mystery switch' was not just dead, but was in fact wired to activate the kitchen circuit. It wasn't a two way switch, like one would use in conjuction with another to have either turn the lights on or off. Instead, IT was just a switch that turned the circuit on or off and when off, the normal kitchen switch didn't do anything. Apparently whoever did that, thought it was a short cut to into actually walking into the kitchen; and, apparently they were too cheap to buy a proper two-way switch.

Sure enough I went back to the entry way and found the tape I placed there removed and the switch in the off position. I flipped it, went to the normal light switch and everything now worked fine! I asked my wife about ti and found she had cleaned the entryway that day and apparently in the process bumped the switch, found a tape on the floor and not knowing where it came from, just dumped it in the kitchen trash container.

I've since properly fixed the switch, mystery solved!

CWS

[LCHIEN]

Switches are the basic digital logic circuits.
When you want to provide Switch A AND Switch B must both be on to operate, we wire them in series.
When you want to provide EITHER Switch A OR B must be on to to active the circuit, we wire them in parallel.
When you have the case where you want to be able to toggle the circuit on from either end, that is called an EXCLUSIVE OR and that's when the three way switches are used at either end.