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参考一下UL2021:0 f; k6 ]; n( c
15.2 Protection of wiring3 L1 B- l* x! \! B3 n: a- v
15.2.1 The wiring and connections between parts of a heater shall be protected or enclosed, except that
/ v& M9 L) g6 x0 a# ia length of flexible cord may be employed for external connections, or for internal connections that may8 ?1 Y: g! i3 k) C. \- R4 j" p
be exposed during servicing, if flexibility of the wiring is essential.
5 c$ j" y/ m; a3 b( C- X' B1 G15.2.2 The internal wiring of a heater in the vicinity of a lampholder that accepts either an infrared lamp
( h y; I) e3 N1 c! z' |) Dor an ordinary lamp:9 w: Q( @8 p' @- Z
a) Shall be a jacketed type at least equivalent to Type SP-2 flexible cord. Asbestos-insulated
! z- I: D+ m. f9 e9 i( }& p* xwiring and appliance wiring material is not acceptable unless provided with sleeving or tubing.# y) k6 ~+ `( ^
b) Shall be routed along the metal surface of the heater enclosure and shall be so secured as
) ^% t+ T2 w& A: hto minimize the likelihood of its being hooked or grasped.
& G3 t% \+ \: K0 \: V( o15.2.3 A conductor utilizing beads for insulation shall not be used outside an enclosure.( g# U5 f: \( H9 O7 i @
15.2.4 Internal wiring that is exposed through an opening in the enclosure of a heater is considered to be
8 r7 w3 ` F# J/ t mprotected as required in 15.2.1 – 15.2.3 if, when judged as though it were film-coated wire, the wiring( Z9 F5 S2 \8 W0 c4 S2 u; L
would be acceptable according to 7.17– 7.20. Internal wiring within an enclosure is acceptable if, even
# K) i2 T* h# L& o( Jthough it can be touched with the probe, it is so protected or guarded that it cannot be grasped or hooked% H/ v1 w: q1 o
in such a manner that it could be subjected to stress. |
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