Re: Home and garden projects
 

Older houses are especially prone to max load problems. Years ago 60 and 100amp main panels were common. Now big houses have two 200 amp panels. When I started wiring my present house I thought my 200 amp 30 slot panel was enough but ended up adding a sub panel in center of house and sub panel in detached garage. The sub panel in the house made wiring a lot simpler with shorter runs. For any amateur like myself thinking of wiring their own house or homeowner that wants to better understand home wiring I recommend the latest edition of Rex Cauldwell’s “Wiring a house”.

Re: Home and garden projects
 

Thank you for the recommendation, I will have to look into that.

100A service is still relatively common, but pretty much necessitates the use of gas for the stove and water heater, and in practice you have to upgrade to a 200A service if you want a central AC system.

Re: Home and garden projects
 

Thank you both! Appreciated!

Our situation -

65 m² 4th floor apartment. Block originally built in 1929. 25 apartments. Very big box in the main entrance hall marked 380 volts, 3 phase.

Water heating is gas. Washing machine but no dryer.
Everything else electric.
In November we replaced a 2 Kw panel heater with a 1.8 Kw flame effect heater.
Otherwise no other changes.
Everything fine until this last week.

We have had the odd trip before, but only very rarely.

Main breaker is rated at 32 amps. Individual circuit breakers at 16 amps.

We have been planning to uprate our supply but are waiting for the block's cables to be replaced.

Thanks for your assistance!

Re: Home and garden projects
 

Now here's the other mystery!

Every now and then something goes "clunk" in our fuse box, a slight buzzing starts and a little light comes on. After a while there is another "clunk" and the buzzing stops and the light goes off. This seems to happen both by day and in the night and seems completely at random. It has always done this.

Yesterday I noticed, just before resetting the main breaker, that it was doing this thing, when in theory there was no power going through!

Re: Home and garden projects
 

Forgot to mention - we have 3 ceiling fans, not in use since the end of October.

Re: Home and garden projects
 

When I made my first post I was thinking worst case possibilities like intermittent shorts when it is more likely just operating near capacity where an infrequent combination of device usage trips the breaker. The fact that it’s becoming more frequent would warrant a closer look for safety and peace of mind. Mice rats and squirrels can chew up wires very quickly. My sister parked her car at her house in Indiana and in one day squirrels built a nest under the hood using insulation from her spark plug wires.

Re: Home and garden projects
 

I agree with Ddsrph - with a 32A main breaker, you are going to bump up against that limit frequently, and if your "everything else" includes a standard 30" stove (cooker), them I am extremely surprised that you aren't tripping the breaker every time you use the oven. .... So if, as you say, the individual circuit breakers are 16A, surely you don't have a full-size stove on a 16A breaker? :unsure:

Oh, and you say your apartment is "65m^2" .... What country are you in? I have been assuming "US", but if you're not in North America, and so have a 230v supply, your power/ breaker situation isn't quite as bad as is you were on a US 120v supply.

Re: Home and garden projects
 

All of this.

Additionally, if you are actually tripping that breaker, they do wear over time, so increased frequency is possible even if not down to an actual fault.

Re: Home and garden projects
 

A hazard indeed! Up here on the top floor I don't think we have any unwanted visitors!

We have had the odd trip before, with, as you suggest, everything on, but very rarely.
We have an oven and hob which comes off the same (16A ?) plug which has always been ok - except when it's on (with everything else), switching on the kettle seems to trigger a trip - but, as I say, previously very rarely.

When the management announced the forthcoming upgrade they asked if we wanted to increase the 32A and of course we said yes.

Meanwhile, electrician is calling either Wednesday or Thursday.

Naturally I shall let you know what he says.

Again, thank you both for your assistance!

PS: No problems today (so far :fingerscrossed:)

Re: Home and garden projects
 

Yes, a kettle would frequently put you over 32A total power draw. 32A on 120v is basically two "maximum" (1,800w) appliances, such as a kettle, heater, or many power tools - my hammer drill, angle grinder, and bench-top plane are all at, or close to, 1 800W. I expect your oven is also a "maximum" appliance too.

One thing you might not realise, is that breakers don't always trip right at their rated power capacity, so you might be able to draw, say, 40A for a minute or two and not trip the breaker.

Re: Home and garden projects
 

That's interesting, probably explains why we have frequently got away with "maximum demand" situations!

I guess the oven / hob must be rated at not more than 3.5 kw.

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By the way Pulaski, mentioned microwaves - ours is 750 W, is that output or input (draw)?

Re: Home and garden projects
 

The rated power (watts) is how much an appliance draws, so current (amps) x voltage. However microwave ovens are relatively inefficient at turning the input energy into "cooking effort" -the microwaves that actually cook the food, are typically in the 50%-65% range; and the efficiency also slowly declines as a microwave oven ages.

FWIW, your microwave is relatively low power, so I assume it is a counter-top design. "Over the stove" microwaves, combined with an air filter/ extractor are usually either 1,000W or 1,200W.

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Thanks. Yes, counter top design.

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Saw your earlier comment about a 30" stove, ours is 60cm (24").
More importantly it seems like that only the oven runs off the 16A plug, the hob must have been hardwired in - somewhere / somehow!