System Impedance

[Electro-tech]

Hi Guys found this in a Ariston 9.5kw Water heater instructions quote ''The product should be connected only to a supply with the relevant system impedance no more than 0.237 ohm. Restrictions to connection may be imposed by the supply authority on the use of equipment in the actual relevant system impedance at the interface point on the user's premise exceeds 0.237 ohm. '' Open to takers!

 

[James]

I would interpret that as max loop impedance from live to N

 

[Electro-tech]

I was leaning towards the line impedance, but why a limit of 0.237ohms ?

 

[James]

Possibly that they have calculated that any more than that can cause volt drop and poor power quality when the heater cycles on and off?

 

[Electro-tech]

Possibly that they have calculated that any more than that can cause volt drop and poor power quality when the heater cycles on and off?

How many situations could you find a line impedance low enough in the first place. How many have been fitted regardless ? Unless like you say the line impedance of the length of cable from the C/Unit to the heater.

 

[James]

Honestly, I have no idea, it was kind of an educated guess