LH-BX (nisa 36) jerin masu karewa mai karewa (wanda ake kira SPD daga baya) ya dace da IT, TT, TN da sauran tsarin samar da wutar lantarki na tsarin rarraba wutar lantarki mai ƙarfi AC don kare walƙiya kai tsaye, walƙiya kai tsaye ko wasu haɓakar wuce gona da iri.
Masu kare hawan hawan matakin mataki na biyu da na uku da masu kariyar gwajin karuwa na Class II dangane da ma'aunin IEC61643-1. SPD yana da yanayin gama gari (MC) da hanyoyin karewa na yanayin banbance (MD).
Samfuran sun cika ka'idodi kamar GB/T 18802.11 da IEC61643-1.