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本帖最后由 lanfeiyuner 于 2015-9-11 14:27 编辑
因为说没有前后文,把整段话附上,请问红色那句怎么理解?
5.2 Access covers
5.2.1 For a unit used as a load center, a cover that gives access to a fuse or other overload-protective
device, the functioning of which requires renewal shall be hinged. A hinged cover is also required for a
unit when it is required to open the cover in connection with normal operation of the unit. The cover shall
not depend solely upon screws or other similar means requiring the use of a tool to hold it closed;
however, it shall be provided with a spring latch or catch, or a hand operable captive fastener. Live parts
shall not be accessible when the cover is open.
Exception No. 1: A cover is not required to be provided with a hinge when the only overload-protective
devices enclosed are:
a) Supplementary types in control circuits and the protective device and the circuit loads are
within the same enclosure,
b) Supplementary types rated 2 amperes or less for loads not exceeding 100 volt-amperes,
c) Extractor fuses having an integral enclosure, or
d) Protective devices connected in a low-voltage, limited-energy (LVLE) circuit
Exception No. 2: A cover is not required to be provided with a hinge for an enclosure that contains no
user-serviceable or -operable parts and which is provided with a marking in accordance with 64.6
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