Some pun on "now we're cooking with gas"
December 4, 2023 9:53 AM   Subscribe

Should my stove have the ability to control the electricity in half of our apartment?

Long story short, we are getting renovations done, and at some point a fuse was blown. This fuse seems to be behind approximately half of the outlets in the apartment, and somewhat confusingly is found not in the apartment itself, but in the boiler room in the basement, which made it rather hard for the contractor to find it, leaving us without power in half of the outlets for the weekend.

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Scene: Saturday morning, in the kitchen.
Enter stage left HUSBAND ready to make coffee. Husband takes kettle, fills it with water, puts it on the stove, turns it on and walks to living room.

HUSBAND: How strange, the lights that were plugged into the outlets are working again. It must have been fixed by our building manager! Let me text the contractor, and then check on the hot water.

HUSBAND walks back into kitchen, and notices that the water is not yet hot.

HUSBAND: Strange, why isn't the stove working? It worked last night...

HUSBAND turns the element off then on, and notices the lights turn on and off at the same time. HUSBAND is concerned. Very concerned

---------------------

So anyhow, we replace the fuse and all is well. But... is this normal? It seems extremely weird to me that a blown fuse would allow the elements of a stove (technically, half the stove) to be the "switch" for a circuit. The contractor called an electrician, and they both seemed somewhat relieved that this was the case, and both claimed this is entirely normal behaviour.

For what it's worth:
* This is an apartment in Sweden
* The apartment is in an older building (ca. 1912), but the apartment itself was added on in the 1980s
posted by vernondalhart to Home & Garden (5 answers total)
 
This failure mode is the reason modern circuit breakers disconnect all phases of a branch circuit at the same time even if the overload was only on one phase. Leaving the branch partially energized enables all kinds of back-feeding shenanigans exactly like you saw -- eg by turning on the stove you connected a load between a live phase and a dead phase, which sends current into the dead phase which lights up the lights on the dead branch.
posted by range at 11:00 AM on December 4, 2023 [3 favorites]


FWIW, this was how my apartment worked when I took it over in 1999. I had most of the wiring redone, since some of the stuff was dangerous, but some elements were so confusing that the electricians gave up and the owner of the building wasn't ready to do a grand purge. We still have issues. I think a lot of old buildings have sort of a patchwork of solutions rather than a meaningful system.

For instance, my electrician has advised me to not use the dishwasher and the kettle at the same time. So in our case, it is not the stove, but the dishwasher that functions as a switch.

The solution is to clear it all out and start over. But that is a really expensive solution if you can make do with less, like not boiling water and washing dishes at the same time.

At our family farm we have similar problems, but they are actually easier to identify. We need to insulate and close off the roof on part of the building, to prevent birds and mice from getting in and harming the wires. I have no idea why they do this, but they do. Again, the price for this is very high.
posted by mumimor at 11:01 AM on December 4, 2023


In modern electricity runs, the stove is on a separate circuit, but in older days, who knows? There were no rules.
posted by The_Vegetables at 12:05 PM on December 4, 2023


For instance, my electrician has advised me to not use the dishwasher and the kettle at the same time.

Your dishwasher and your kettle are single-phase consumers, but when your electrician says not to use them at the same time, it's because they're on the same circuit and running them both would overload it. There are power strips with a priority switch: two sockets, and you use one for, say, a kettle, the other for a hot-water tank under the sink (has to be something that doesn't care about not getting power for a couple of minutes; a dishwasher will likely object). When the kettle is switched on, the other socket is switched off, and back on when the kettle finishes.

Vernondalhart's stove is connected to TWO circuits because of its current draw, and switching on the element for the kettle happens to use current from both circuits. As one circuit is dead because of the blown fuse, the current is only drawn from the other circuit but the dead circuit is now connected to the live circuit via the stove's switch and the heating element. And in this particular case all the current apparently goes from the live circuit through the switch and the element to a couple of lamps. As those lamps add up to maybe 100W, there's just those 100W going through the element (somewhat simplified, but otherwise I'd have to bring Ohm and Kirchhoff into this answer) and it would barely heat up.
posted by Stoneshop at 2:07 PM on December 4, 2023 [2 favorites]


Sounds like a fuse or circuit breaker in the main disconnect for your apartment blew. Its in the boiler room because it is grouped with all the other services in the building. It's not unheard of for a old fuse (and yours could be as old as your apartment) to just decide to quit without any significant overloading event.

IIRC Sweden has 3 phase power to homes. And new stuff has an rcd on each phase that can trip independently so an rcd trip doesn't take down the whole house.

Generally speaking this condition isn't dangerous though the undervoltage that often results can damage equipment sometimes.
posted by Mitheral at 3:08 PM on December 4, 2023 [1 favorite]


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