Electrode gap used in Arc Flash calculations....where does this info come from ? 1

[bdn2004]

Does anyone have a chart or something to back up where this info comes from ?

For example...
On a 480V bus the selection in EasyPower is either 25mm (.984 inches) or 32mm (1-1/4")
On a 34.5 kV bus the electrode gap is defaulted to 254 mm (10 inches)

This effects the calculation.

 

[davidbeach]

Look at the spacing between phases in the gear.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[dpc]

Default values for arc gap come directly from IEEE 1584 guide and are a function of voltage level and type of equipment. As David says, they measured bus spacing for different types of gear from different manufacturers. The default values in the software are taken from IEEE 1584, but can generally be adjusted if you have reason to do so. The IEEE 1584 standard only covers up to a maximum of 15 kV, btw. Above that, EasyPower reverts to the old Ralph Lee equations.