Hello all,
Sorry for the latency in my post, but here's my 2¢ anyway! ;)
I have many Motor Connection Drawings posted on-line at ECN, which may be of assistance to Members needing references.
In particular per this Topic, check out this page...
You are correct in not accepting the Sales Person's example here!
24 KVA @ 480V 3 Phase Electric Heater connected to a Wye System equates to 8 KVA per Line (Phase); which equates to apx. 28.88 Amperes per Line.
Suggest to use a 3 Pole Contactor, with 40 Amp Resistive / Tungsten rated Contacts...