TY - BOOK ID - 85700715 TI - "C37.21a-2020 - IEEE Standard for Control Switchboards--Amendment 1: Control and Secondary Circuits and Devices, and All Wiring" PY - 2020 SN - 1504465725 9781504465724 PB - IEEE DB - UniCat KW - Switching circuits. UR - https://www.unicat.be/uniCat?func=search&query=sysid:85700715 AB - ER -