delta and y connections

[Redskinsdb21]

If im given a delta 240/120 volt 3-phase load, and I want to model it as one phase.....line to neutral as if there is a neutral, like we can also do with WYE.....would I divide by sqrt(3) to get the line to neutral voltage value to use or would I use 120 volts.....when calculating parameters of the single phase equivalent circuit of the 3 phase problem?