Suggest T&B “Kopr-Shield” or Fel-Pro C5A for conduit threads. Don’t expect a perfect watertight seal, but preservation of raceway continuity during faults.

Page 3 of www.tnb-canada.com/catalogues/pdf/en/t_b/fittings_01a_eng.pdf
or www.newmantools.com/felpro/c5a.htm

For hazardous-location installations, Crouse-Hinds HTL compound is useful.