Motor Burned Without Tripping My ELCB Circuit Breakers

On overheated element such as this would in time burn through some insulation, resulting in arcing between parts. An arc does not necessarily draw a large current, so a regular CB might not trip. Various types of ground fault detecting CBs exist that can respond to such faults.

IT IS SIMPLE TO UNDERSTAND. AN ELCB, IF PROPERLY INSTALLED AND TESTED, WOULD ONLY OPERATE IN CASE OF AN EARTH FAULT. A THROUGH FAULT OR OVERLOAD OF ANY INTENSITY WILL NOT OPERATE IT, BUT A SMALL EARTH FAULT OR LEAKAGE CURRENT OF 30 TO 300 mA WOULD OPERATE IT INSTANTANEOUSLY TO ISOLATE THE FAULTY CIRCUIT. IT IS PRETTY SURE THAT NO EARTH FAULT WAS INVOLVED IN YOUR CASE. BUT IF EARTH FAULT WAS INVOLVED, THE ELCB WAS NOT PROPERLY INSTALLED/TESTED. NORMALLY PROPERLY RATED CIRCUIT BREAKERS ARE CONCURRENTLY USED TO TAKE CARE OF OVERLOADS AND SHORT CIRCUITS IN THE DISTRIBUTION BOARDS.

Right on the button and a GA from me.

Oops, my fault. I'm used to the terminology "GFCI" (ground fault circuit interrupter), and I misunderstood "ELCB" as a conventional circuit breaker, as for overcurrents or short circuits. And my apologies. I should have looked more closely, and and understood "ELCB" correctly. Thanks for setting me straight (GA).

Thanks also to Andy, who pointed out a few posts later that I was wrong (GA).

Wrong.

A perfect answer (except for the CAPS, PLEASE DO NOT SHOUT!!!)

I have given you a GA, someone else gave you an off topic (probably because you were shouting too much!).

can u provide a little more details abt the installation of the distribution board of ur apartment........havent u installed mcb along with elcb....?if not , then thts the problem ....an elcb will not trip on overcurrent or short circuits........it only trips when current flows through neutral wire (earth fault).......probably there was an overload condition and thts y ur motor heater was burnt......jus provide a lil more details.........nowadays a new type of elcb or rccbs are used which provides protection from overcurrent and earth leakage currents...they r called rcbo....u can use tht

The problem is related to lose contact and local heating in the socket due to IR loss and heating in the socket. In such cases the burning is not due to over current. The ELCB provides protection against short ckt and over current and not local heating

N.C.AGRAWAL

Simply not true...

An "Earth Leakage Trip Breaker" provides a trip ONLY when there is a "leakage" to earth.

Some also have "over current" sensing built in as well, I do not know what the full correct name is then, but assuming he had one of these of say 30 amps, then 25 amps can cause a fire, but would not trip the breaker.......

He really needs an "over temperature" sensing built into where the water heater is.....

I expect that the water heater's normal current is well below 30 amps, so he should install a current breaker, just for the heater, dimensioned to trip with say a 10-15% larger current than the heater normally takes.....

i don think thts completely true...i meant the second part..................elcb doesnt give protection from short circuits or overcurrents.............its rccb which gives protection from overcurrent but not elcb........an mcb is usually connected before the elcb in any distribution system in order to protect frm short circuits or over currents.............

I am confused a little about the "Motor" ! Where this motor comes in a water heater?

In any case, Check the earthing of the Motor and the water heater body.

An ELCB of the old type that operates on voltage drop when there is a leak to ground can easily become faulty from previous trippings (specially if caused by shortcircuits to ground). A Residual Current Circuit Differential Circuit Breaker is the best because it is not affected by massif short-circuits to ground.

Allways check them once every 3 to six month or when you remember: Press the test button to trip them. If faulty they either do not trip or will not reset!

32A @ 240V = 7680W.

What was the power rating of the motor, and why wasn't it protected with a motor overload protective device of lower breaking capacity downstream of the 32A breaker?

Circuit breakers do not protect electrical loads from overheating. They will only trip when the current exceeds its rating by another 10% 0f its designated rating.

The thermostat switch on the the unit should have tripped the power to the unit and motor.

Get a new unit.

Despite my earlier misstep, I am still interested in the OP's question of why his ELCB failed to open. The GFCIs I mentioned will trip at around 5 ma of differential current. I think the OP later mentioned ELCB differentials of something like 30-300 ma, which is not as sensitive.

The specific type of fault I mentioned in post 1, an "arcing ground fault" (which is exactly what could occur in an overheated heating element), can take place with stray or leakage currents of less than 30-300 ma. Over time, a low-current spark could melt some wiring or start a fire without being detected by, say, an ELCB. Allen-Bradley, for one, makes an arcing ground fault detection system that may be more sensitive (and more costly) than typical ELCB methods.

This may be a candidate explanation of the OP's problem; or it may be yet something else.

[I too am still wondering about where the motor is in this water heater.]

Yes. What is the motor doing there?

Also, an RCD cb with 30 mA sensitivity is usually good enough for a water heater element leakage. An element failure because of water shortage in the heater is worrying since the heater should have some protection against the heater getting starved from the water (some kind of valve to prevent water going out without replacement...many questions to clarify for a proper advice...