RHH on NEC / UL (USA)-järjestelmän kaapelin tyyppimerkintä: R = Thermoset (originally rubber) insulation; HH = High heat resistant, 90 C; RHH = Thermoset (rubber-type) high heat-resistant building wire, dry and damp. 600 V, 90 C dry and damp. UL 44; NEC Article 310.