Decoding Electric Fuses

[coconut]

In a rented house, the fuse box has markings I'm not familiar with.

What would 5 KA also M 5 translate to in Amps?

Recently installed a 6000 watt water heater that is not reaching the required temperature, so thinking might have to install a 30 amp fuse but no idea of what 5 KA or M5 translates to in amps.

Any info appreciated

[Crossy]

Probably best to post photographs, the numbers mean little without a context

Do you actually have fuses or MCBs (breakers)? Photos of these would also be helpful.

Simply uprating the fuse will not increase the temperature of your water, you may be undervoltage or overloading your supply with your 6kW heater. What meter do you have (5/15, 15/45 or 30/100)?

[Rimmer]

Its to do with the tested fault levels.

A normal low level, low life circuit breaker such as an ITE, MEM, Square D, product tested to BS would give a rating of M3 if a similar breaker is tested to IEC or NEMA the same breaker can have a rating of M6.

The DIN rail mounted breakers such as BBC and Tchino are usually M6 tested to IEC the larger DIN rail breakers go to M9.

Nothing at all to do with the amperage rating of the breaker.

Clear? Nope, I did not fully understand it either and I sold the rotten things for 20 years.

[Crossy]

Clear? Nope, I did not fully understand it either and I sold the rotten things for 20 years.

555, that's why I suggested photos of the breakers / fuses, we stand a chance of getting the relevant info to assist with the water heater problem.

[coconut]

Rimmer, if I was confused before, your post was like encrypted secret information to me.

Perhaps I need new glasses, but upon trying to take pictures of the fuse box as Crossy suggested, realized that there were amp readings above the 5KA & M5 markings. Just did not see them at first, so the hot water heater has only a 20 amp fuse/breaker.

Also, the owner, said that the house has a 3 phase(whatever that means) electric system and the house has a 30/100 electric meter.

In our bungalow, down south, have a 15/45 electric meter and a 30 amp fuse/breaker to a 6000W hot water heater, which works great. Can get 40-43 degree hot water at full water pressure.

Here, in the north, can only get warm water at very low water pressure. Yes it is colder here, 13 degrees yesterday morning,

Crossy, do you think a 30 amp fuse/breaker would solve the problem. Really miss my hot water.

Will now try to attach a few pictures. Thanks for the replies.

The Nr 2, 5KA, 20 amp breaker marked daughter room is where the hot water is located. Also there is a 25 amp fuse/breaker on-off switch next to this heater. Sorry for the fuzzy first picture.

Edited November 18, 2008 by coconut

[Crossy]

Your 6kW heater should have a 30A breaker (about 27A draw) but simply replacing the breaker won't do the trick.

You need to check the cable size going to the heater, it should be 6mm² for your heater, if you try just using the 2.5mm² cable that was originally wired to the 20A then you could start a fire!!!!

I'm surprised that the 20A breaker isn't dropping when you use the heater so you need to check the heater connections. Take the lid off and snap some more pictures, probably easier than describing what you see.

Edited November 18, 2008 by Crossy

[Rimmer]

Your 6kW heater should have a 30A breaker (about 27A draw) but simply replacing the breaker won't do the trick.

You need to check the cable size going to the heater, it should be 6mm² for your heater, if you try just using the 2.5mm² cable that was originally wired to the 20A then you could start a fire!!!!

I'm surprised that the 20A breaker isn't dropping when you use the heater so you need to check the heater connections. Take the lid off and snap some more pictures, probably easier than describing what you see.

But don't put your fingers inside near the shiny coppery things.

Nice pictures though

Edited November 18, 2008 by Rimmer

[coconut]

Crossy, pictures as requested.......... Rimmer, thanks for the warning, always try to keep fingers out of unknown places. The red cable, as I'm sure you know is the ground cable.

[Crossy]

Red = Ground = Wonderful, but at least you have one

It's difficult to tell the size of your incoming from the photo, but never mind. Adjust that black wire (power off) so no copper is visible.

Do you have a meter? If so check the voltage between Black and Grey, both with the water running and without, report voltages (should be 220V AC).

You say you only get a trickle, maybe there is not enough water flow to fire up the heater, check your plumbing (in and out correct way round?).

Edited November 19, 2008 by Crossy

[longball53098]

If the voltage tests Ok try checking the inlet filter for debris. I just cleaned one on our condo heater and it was all gunked up restricting water flow