Voltage Drop at the CU supply

[mbga9pgf]

Quick question,

What are the allowable limits from a supply side in terms of voltage drop?

I recently measured the voltage drop at the CU with my 10Kw power shower running.

RMS value was 231 volts prior to turning on, 222 volts with it on. Approximating a 43 amp supply to the shower, this seems to indicate a 4% drop in volts. The supply is supposed to be rated at 80A. assuming the volt drop is proportional, this indicates my suppy voltage is dropping 7.5% at max rated load.

What do you all think? Abnormal or normal? I live in a rural area on overhead power supply.

Thanks in advance.

 

[ericmark]

The rules are standard voltage is 230vac +10% -6% at meter head. Plus in house a further 5% for power or 3% for lighting.

 

[holmslaw]

..

 

[plugwash]

Something else to consider is fuse rating is not the same thing as agreed max demand, afaict they only have to maintain the voltage within tollerance up to your agreed max demand.