APL-5 Series Limit Switch Box 
Installation Operation & Maintenance Manual 
Doc No. : HUMG-APL5-16 Rev0  Page  5 / 13 
4.2. Pre-Installation for use in potentially explosive atmosphere 
Installation,  commissioning,  maintenance,  repairs  and  modification  work  must  only  be 
performed by qualified personnel with extensive knowledge on how to work on explosion-proof 
electrical equipment. 
Warning  :  Read  this  installation  and  maintenance  manual  carefully  and  completely  before 
attempting to install, operate, or troubleshoot the HKC product 
4.2.1. Cable Connection 
①Sealing  devices  must  be  used  and  shall  be  fitted  directly  at  enclosure  wall  when  using
conduit.
②Cable glands shall be suitable for the environment and shall be certified as flameproof if
used in Zone 1 application of IECEx scheme in order to connect outside electric wire.
③Cable glands and conduit to be installed minimum 8 full threads and the length of thread
is minimum 8mm.
④“Warning”  :  Please  be  sure  that  user  should  select  the  appropriate  cable  glands  and
minimum 2SQ of wire  for  fear  that the proper using temperature of cable entry and wire
way exceed 70 ℃ or the blanching point is over 80 ℃.
⑤When cable entries or conduit entries are not used, user or installer shall close by certified
blanking elements(stopping plugs) so that the flameproof properties of the enclosure are
maintained.
4.2.2. Groundings 
①Always ground the enclosure in accordance with local electric codes. The most effective
enclosure grounding method is a direct connection to earth ground with minimal
impedance. Methods for grounding the enclosure include:
Internal ground connection : The internal ground is located inside the body .
External ground connection : The ground bracket is located on the side of body.
       (Min 2SQ wire required) 
4.2.3. Special Condition for safe use (“X” marking) 
①Electrostatic discharge from window(over 1GΩ) may cause the ignition on the explosive
gas  atmosphere.  By  adapting  the  conducting  window  bolts  make  reduce  the  risk  from
electrostatic discharge.
②Before  installation  or  maintenance  products,  shut  off  incoming  power  and  grounding
should be connected.
③The  window  must  only  be  cleaned  with  a  damp  cloth  in  order  to  avoid  ignition  hazard
caused by static electricity.
4.3. Initial inspection 
When the user receipts the product, inspect the condition of the product and ensure the name 
plate comparing with order sheet. 
4.3.1. Remove  packing  wrap  or  wooden  box  carefully.  Inspect  the  product  for  any  physical 
damage that may have occurred during shipment. 
4.3.2. Check  the  product  specification  with  product  ordered.  If  an  wrong  product  have  been 
shipped, immediately report to our coordinator.