Appliance Ratings and 13A plug tops

statter:

Hello

I looked last year for portable heating and not surprisingly there was little above 2.5kW rating.  All the old 3kW stuff has long gone.

I was surprised however to find a wide range of steam irons rated at 3000W and even 3100W.  (that's almost 13.5A at 230V).  I realise of course that irons are likely to be much more intermittent than heating and that 13.5A is very unlikely to blow a 13A fuse but it cant be good practice to overload plug/ socket like this.  A decent ironing session can still be hours ……   OFC at 240v its under 13A but 230v has been the standard for ages now.   In my experience many socket/ plug combinations are marginal approaching their rating so deliberate overloading will only make matters worse over time.  I would have thought that these appliances wouldn't qualify for CE marking and couldn't be sold legally?

The power range is stated (according to the standards) at the nominal voltage, or highest nominal voltage, stated on the rating plate. In the UK, appliances are typically rated at either 230 V (so the maximum appliance rating is 3 kW ... 230 x 13 = 2990 W, the element resistance at operating temperature being 230/13 = 17.69 Ohms) or either 240 V or 220-240 V (so the maximum appliance rating is 3100 W ... 240 x 13 = 3120, the element resistance at operating temperature being 240/13 = 18.46 Ohms)


In use, the actual current of the appliance may go up or down.


Our calculations for BS 7671 (WIring Regulations) are usually done at 230 V.


The actual mains voltage can be higher, though. WIth supplies according to the ESQCR, the voltage may be as much as 253 V. At this voltage, in appliances with resistive loads, the actual load currents will be higher, so will the power output will also increase, with the two examples above:

• 3 kW, 230 V iron: Current = 253/17.69 = 14.3 A, power = 3618 W

• 3.1 kW 240 V iron: Current = 253/18.46 = 13.7 A, power = 3467 W

What might be surprising when you see this, is the 3 kW iron actually uses more power than the 240 V 3.1 kW iron !!!


Is this a problem? Definitely not, we do our calculations at 230 V, but the actual currents may be higher if the voltage is higher (or lower if the voltage is lower) The cable and protective device ratings can manage this tolerance.


Similarly, the voltage may be below the nominal rating. At the lower voltage (the utilization voltage in the UK, for ESQCR supplies, after voltage drop in the electrical installation, can be as low as 204.7 V), the power used by the irons, and hence their currents, also come down - in this case again, the 3 kW 230 V iron will use more current and power!

Does anyone know if there is a BS or EN for small appliances?

 

statter:

Hello

I looked last year for portable heating and not surprisingly there was little above 2.5kW rating.  All the old 3kW stuff has long gone.

I was surprised however to find a wide range of steam irons rated at 3000W and even 3100W.  (that's almost 13.5A at 230V).  I realise of course that irons are likely to be much more intermittent than heating and that 13.5A is very unlikely to blow a 13A fuse but it cant be good practice to overload plug/ socket like this.  A decent ironing session can still be hours ……   OFC at 240v its under 13A but 230v has been the standard for ages now.   In my experience many socket/ plug combinations are marginal approaching their rating so deliberate overloading will only make matters worse over time.  I would have thought that these appliances wouldn't qualify for CE marking and couldn't be sold legally?

The power range is stated (according to the standards) at the nominal voltage, or highest nominal voltage, stated on the rating plate. In the UK, appliances are typically rated at either 230 V (so the maximum appliance rating is 3 kW ... 230 x 13 = 2990 W, the element resistance at operating temperature being 230/13 = 17.69 Ohms) or either 240 V or 220-240 V (so the maximum appliance rating is 3100 W ... 240 x 13 = 3120, the element resistance at operating temperature being 240/13 = 18.46 Ohms)


In use, the actual current of the appliance may go up or down.


Our calculations for BS 7671 (WIring Regulations) are usually done at 230 V.


The actual mains voltage can be higher, though. WIth supplies according to the ESQCR, the voltage may be as much as 253 V. At this voltage, in appliances with resistive loads, the actual load currents will be higher, so will the power output will also increase, with the two examples above:

• 3 kW, 230 V iron: Current = 253/17.69 = 14.3 A, power = 3618 W

• 3.1 kW 240 V iron: Current = 253/18.46 = 13.7 A, power = 3467 W

What might be surprising when you see this, is the 3 kW iron actually uses more power than the 240 V 3.1 kW iron !!!


Is this a problem? Definitely not, we do our calculations at 230 V, but the actual currents may be higher if the voltage is higher (or lower if the voltage is lower) The cable and protective device ratings can manage this tolerance.


Similarly, the voltage may be below the nominal rating. At the lower voltage (the utilization voltage in the UK, for ESQCR supplies, after voltage drop in the electrical installation, can be as low as 204.7 V), the power used by the irons, and hence their currents, also come down - in this case again, the 3 kW 230 V iron will use more current and power!

Does anyone know if there is a BS or EN for small appliances?