690v 3 phase application lead wire rating

[BigMotorGuy]

Stupid question, but I have an application going into a 690v 3 phase system, so since the actual voltage to ground on any of the 3 legs is 690/sqrt3 = 398.4v using 600v rate wire is ok right?

 

[waross]

You have over 600 Volts phase to phase. Use 1000 volt rated wire.
My code requires wire to be rated for the highest voltage present, NOT the highest voltage to ground.
Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[BigMotorGuy]

TBE, in regard to the peak voltage versus RMS, wiring ratings are RMS values, so I don;t believe that is an issue.

Waross, if each individual wire is rate at 600v between the inner conductor and (in this case) the out SST armor (i.e. ground), then having 2 cables next to each other (i.e. the 690v) has 2 layers of said insulation. The problem comes in that this is specialty wire that is not available in 1kV rated. Is my thinking way off here?

 

[waross]

RMS values are used for cable voltage ratings.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[itsmoked]

BMG; I believe the concern is one cable insulation damaged or cable running across or touching a different phase lug would land you seriously underrated.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[TugboatEng]

Is this armored shipboard cable? MIL-C-24643 specs a 1kV rated single conductor armored wire. LSSSGA