Fitting An Electric Shower Question..........(Again)

[nattydread]

my teerak has been gifted a one year old Sharp WH404 electric shower unit (3500 watts) by her cousin who had it fitted in a rented condo then removed it when she left.........she wants to fit it into her parents bathroom,so heres the situation

the electric meter is a 5/15 amp

there is a new safe t cut box installed recently (courtesy of u know who) which has an unconnected spare 35A and 20A fuse

from reading the forum am i right in saying to use 4mm wire from the fuse box to an on/off switch outside the bathroom then run the wire in some plastic trunking to the shower unit?.......use the 20A fuse in the safe t cut box

connect a 4mm earth wire from the shower to a 2 metre copper ground rod and clamp outside the bathroom window ( all the sockets in the house are 2 pin except the washing machine which also has its own ground rod connected to a 3 pin socket

the shower unit has an elb on it and the safe t cut box has an RCBO inside

Questions

will this set up suffice? (there is an "electrician" coming to do the work )

will the 5/15 amp meter cope with this and would it be advisable not to use the washing machine and shower at the same time? ( there is no aircon in the house just lights, tv etc )......an upgrade meter 10/45 is 8000 baht which is too much cash for them or me to stump up

should i buy some sort of water filter to fit on the inlet pipe?

thanks very much for any advice

[lopburi3]

That should work but you really need to upgrade to 15/45 meter and likely feed line to house as soon as you can. Remember the shower heater does not pull the 3.5kw unless at hottest setting and you can use flow volume to regulate the temperature also.

[Khonwan]

I am not an electrician but have personally installed a few electric showers including a 3500W Sharp model for my mother-in-law a couple of days ago. 2.5mm² cable would be sufficient between fuse (20A) and shower. 4mm² cable is better for the earth/ground (being stronger it is more resilient to physical damage).

If you do not add a water filter (I never have) you can usually unscrew the shower head to clean out any collected matter.

I too would advise you uprate the meter but you should still get by if not operating other appliances whilst showering.

[electau]

Your 5/15A meter should suffice as the HW unit only is in use intermittently. 15A is the rated continuous current rating of the meter, they will accept 100% overloads for short periods , (the accuracy may be affected slightly).

Connect to 20A MCB cable size 2.5sqmm.

Earth, the PE conductor minimum size 2.5sqmm, protect PE conductor from mechanical damage.

Install RCD protection on socket outlets. The internal RCD on the shower heater will be 10mA, your RCBO will be 30mA.

[Khonwan]

Your 5/15A meter should suffice as the HW unit only is in use intermittently. 15A is the rated continuous current rating of the meter, they will accept 100% overloads for short periods , (the accuracy may be affected slightly).

<snip>

I don’t think that is correct. I believe that a 5/15A meter is designed to run continuously on 5A and peak at 15A for short periods.

[electau]

Your 5/15A meter should suffice as the HW unit only is in use intermittently. 15A is the rated continuous current rating of the meter, they will accept 100% overloads for short periods , (the accuracy may be affected slightly).

<snip>

I don't think that is correct. I believe that a 5/15A meter is designed to run continuously on 5A and peak at 15A for short periods.

The second figure is the continuous rating, the first figure is the rating for test and calibration purposes. Eg 15/45, 30/100

[Crossy]

For once I agree 100% with Electau

15A is the nominal rating of the meter, it will likely be fused at 30A or thereabouts (I can't see the rating of the incomer on the box you picture).

[Khonwan]

Thanks to both of you for that clarification.

[Pib]

Your 5/15A meter should suffice as the HW unit only is in use intermittently. 15A is the rated continuous current rating of the meter, they will accept 100% overloads for short periods , (the accuracy may be affected slightly).

<snip>

I don't think that is correct. I believe that a 5/15A meter is designed to run continuously on 5A and peak at 15A for short periods.

The second figure is the continuous rating, the first figure is the rating for test and calibration purposes. Eg 15/45, 30/100

Yeap, agree...and as FYI the way the Bangkok Metropolitan Electricity Agency phrased it in a electric meter request for proposal was: "The current ratings in the price proposal are indicated as "Nominal or test amperes" and "Maximum or class". Rated temperature for calibration shall be 20 degrees C."

[nattydread]

For once I agree 100% with Electau

15A is the nominal rating of the meter, it will likely be fused at 30A or thereabouts (I can't see the rating of the incomer on the box you picture).

the safe t cut box is rated at 50A