Hi All Would like to check if a hdb unit is having 30A main supply (not upgraded), can I use instant electric heater that is spec at 3.6kw? Read on HDB website is 3kw but most models sold in the market are above 3kw, has anyone done that? Also, is it mandatory to use double insulated cable for the heaters and aircon? Because what was laid is the usual 3 core cables (brown,blue n green) without the grey, is this normal? Looking forward to any advises or experiences. Thanks! Ryan