Abstract: An electromagnetic coil construction consisting of a bobbin having a primary winding and a secondary winding, the bobbin having an end flange at either end of the hub and a central separator flange intermediately spaced between the first and second flanges, the separator flange having a through opening into which a thermal sensing device electrically, interconnected in series with the primary winding or a secondary winding is adapted to be interposed whereby the device is in physical contact with both the primary and the secondary winding to interrupt the circuit upon overheating of either or both windings.