Service Breaker Question

I can't tell you what to do and I don't want you to do it wrong, but it sounds to me like you are feeding the water heater with 120VAC.

If the breaker is 230VAC and it's going to a light switch, it would blow out the light bulbs.

The 230VAC water heater needs it's own dedicated circuit.

I'm not an electrician, so maybe somebody else can tell you exactly how to test and wire it properly.

tiger; I believe that Chile has adopted the U.S.A. national electrical code, NEC for wiring in the future, or now! American Wire Gage, AWG #12 wire can be solid, or stranded with THW, or THWN THHN nylon covering is normally rated 20 amps. If main service breaker is 20 amp @ 230 volt you have 4600 watts for use, the water heater rated @ 15 amps would be 3450 watts, leaving 1150 watts for general use, for lighting or ?? the water heater would not be any different in the morning or afternoon, same power used, the second breaker could be the disconnect in sight of the water heater. what brand of circuit breaker are used. perry

Do you know if the thermal heater did work acceptably ever? Or , has this problem been a recent development? I would first measure with amp meter how much current the heater is drawing during the period just before the service breaker blows. You said that the heater is rated at 15 amps. If it is drawing 15 amps or more, the thermal heater is probably bad, old and using more amps or perhaps some one repaired it and used a wrong element that may be for a larger heater. Also measure the voltage at the heater to ground to make sure it has the proper 230v. Low voltage will cause more current.

So if the amps and volts being measured at the heater are less than 14-15 amps and near 230v, then the wiring is the cause of the premature service breaker. I would also suggest that visual inspection of that small wire may have indications of heat from the excess current drawn.

Another thing about water heaters is that they tend to collect silt from the water in the bottom, even in city supplied water systems. Common practice here is to flush out the tank yearly. Removing built up silt will make the water heater work better (more hot water and reheat faster). It may also be the reason the heater has to work harder, drawing more current to heat the same amount of water. Trying running a large glass of cold, let it settle a minute and look at the clarity, then run the same glass full of the heated water, let it settle and see if the heated water is dirty compared to the cold, if so, the tank needs flushed.

Uh, how many elements does the heater have? What's the rating on the heater label? Is there a toaster, oven, coffeepot, etc being used by the first person to shower while the second is using it? Is the heating element shorting to ground after a long expansion?

As someone else has pointed out, there must be a local electrical wiring code to follow. Common sense (and the UK code) suggest that a unit drawing 15A should be served by its own breaker. A 20A breaker is almost certainly too large for your lighting circuits.
The ultimate answer, therefore, is that there should be two separate breakers at the main board. If you really cannot run a second cable to the water heater, then I suggest you replace the breaker nearer the heater with a junction box (there is no point in having 2 breakers of the same rating in series). The junction is fed by the supply from the first breaker. From the junction box one feed goes directly to the heater, and another feed goes to a new lower-rated breaker which serves the lighting circuits.

That scenario does not increase supply current to the water heater.

If you look at the OP's scenario, an under-supply of current was not an issue. The heater was over-heating. My concern was to avoid the lights going out every time the heater misbehaved. I had already pointed out that running a cable for the heater alone (which would avoid overloading the cable) was an even better solution.

PHPH001,

Unlike europe, here in Peru is 220VAC at the source. Everything in domestic electronics, large or small, is 220VAC whether it be the lights or the washer and dryer. Here you have to look at the amp load and the watts. The pole source is 380VAC coming to the house and 220VAC sourced by two wires throughout the entire house. The only ground here is at the pole itself. We are taking built in the early fiftyish so as far as codes for this place its better for the poor people to pay under the table than to have the government to throw them in the street.

I am helping freely to correct this problem without having to out weigh the source of income availiable to pay for the entire house to be rewired. I personally know this situation is entirely miswired but like I said the money is not there. I appreciate all of the comments and opinions and will read them very carefully and use what sounds correct to me. Yes, I am following the local electric codes, what few exist for the area in which the house is located. And, by the way, its not a tank its a heating element encased in a plastic mold of a shower head and the water runs directly over the element to heat the water.

Thanks to all for your opinions, Louis(oceantiger)

I have travelled to a number of different countries, so here is my suggestion:

1.- First check the local codes to make sure that you will not be in violation of any.

2.- Change out the cable not to 12 ga. but rather to 10 ga. The reason is that in Peru like many Latin Countries the line voltages tend to fluctuate quite a bit both above and below the preset voltages. So this way you will avoid overheating of the cables due to the line variations.

3.- The change of the cable size will also help if the installation is in a hot tropical area.

4.- Try to have only one breaker between the main switch box and the heater, and this one try to get a GFCI type unit, that can trip on short circuits due to overheating of the cable, ground faults, etc. Helps protect the person taking a shower.

Thanks for the understanding of this problem and you are correct when you say the electric here is nothing like any where else. The lights here run on 220vac just like everything else and the building I am living in is older than most apartments in New Orleans. I was born and raised in Biloxi, MS and have visited just about all Latino countries and the older cities have the same configuration but the heater is a single heating element encased in plastic mold that the water runs over the element and through the shower head, it is not a tank at all. I will try what you are telling me and see if it works.

Sorry it took so long to reply but if you have been to any Latino country you would know the satellite system for phone, internet and tv are run together and its hard to get somewhere to get an internet signal.

In the process of heating the water, if the water temperature is high enough, on the heating element are forming calcium deposits that greatly decrease the heat transfer, causing the element to overheat. Same as the electric kettle or the steam iron. The quantity of deposits depends on the water hardness, temperature, the time in use, etc. In the kettle you can clean it by boiling vinegar solution. If possible, try to inspect the heating element and if is covered with calcium, clean it up with sandpaper, but be gentle.

Does this picture appear like the one you are having trouble with?

If the breakers are ELCB ( earth leakage core ballance ) type putting two in series is known to cause nuisance tripping.

For Merph

Yes, sorry, always read them first time asking for help. All the years reading this forum I have never posted a question because someone usually posted an excellent answer or a perfect question. But thanks for letting know and it wont happen in the future..

After re reading, I wonder if in Peru 230VAC single pole is standard for a 20 amp circuit. That's what I wish it were here. In that case a lightbulb or fixture, even incandescent, would pull less than 1 amp, and adding the fifteen amp water heater for 16 total would still not be very problematic on one circuit. If you have voltage spikes and poor power quality, it could cause tripping, but there is nothing too dangerous in this scenario. I would correct wire to 12Gauge, even 10 would be worth it, if you are pulling new. My guess is you have a breaker trip when you have amperage spikes up with voltage spikes down., not because the unit is overheating. I agree with the other posters, increase wire size. The resistance element in that shower head is not in danger of damage, it's pretty robust. I would use a GFCI breaker if you can find one, if you decide to replace it.

Your last question does not make sense to me. The breakers won't care what is happening to your main, which is I'm guessing is a 100 amp, or maybe a 50.