How are equipment ratings derived?

[JFletcher]

As I do not live in, do electrical work, or have any UK spec appliances, I cannot answer the question. Ask for the restaurant grill, okay you got me there.

What are you really asking here in this topic? As far as I know, all things are wired, and have ocpd based on nominal system voltages. The only exceptions I'm aware of are motors, which are rated/ labelled 230 / 460 volts, presumably to account for voltage drop on 240 and 480 volt systems.

Most manufacturers base their ratings from nominal system voltages. Some, who knows, like your average air compressor for home use listed at 5 horsepower, but only draws 10 amps on 120 volts. I believe those ratings may be based on Startup or locked rotor current.... or simply wishful thinking. Many portable home generators have similar peak power ratings that are advertised, however their continuous or steady-state wattages are much lower

Take this for example:

32 amps at 208 volts single phase. Is 32 amps the current draw at 208 volts or 229 volts I guess I am asking.

The way that I interpret that name plate is that it draws 28.0A on 3 phase and 32.0 amps on single phase 208. The lower kilowatt ratings for single phase are not on the nameplate. single phase is probably a few amps higher though due to a motor or something running in addition to the heating elements. My wag for the day.

Eta: 32.0 amps appears to be the maximum amperage draw per phase.

all of the numbers appear to be based on 208 volts

 

[MTW]

Take this for example:

32 amps at 208 volts single phase. Is 32 amps the current draw at 208 volts or 229 volts I guess I am asking.

It's always best to check the manufactures specifications when in doubt. Earlier in life I serviced commercial cooking equipment, so I have some history with this type equipment.
This tag is for a 24" electric griddle, which has two 3550W heating elements. It is configurable in the field for a 3Φ or 1Φ supply by changing the element connections on the terminal block provided. Paralleled elements for 1Φ operation, or split across 2 phases for three phase operation (unbalanced operation).

Consulting the literature, the voltage variation is rated for +/-10%. And is meant only for 208V operation for this paticular model. The parts list has elements listed for 4 different voltages, 208,220,230,240. It is expected that you obtain the proper unit for the site voltage, or change out the elements as required, to achieve rated life and performance.

Operating at more than nameplate voltage, will increase current draw with this appliance, as it's plain heating element loads only.

Specifications and parts list can be found here. Specs...Parts.

MTW

 

[FionaZuppa]

Spec sheet & phone numbers
here http://www.garland-group.com/asset/?id=jwrbzx&regions=us&prefLang=en