1. Electrical performance of junction box
(1) Insulation resistance
① Under the standard atmospheric conditions of the experiment, the insulation resistance between any two ends and between any terminal and the metal box should not be less than 5 × 104M Ω.
② After the condition test, the insulation resistance between any two ends and between any terminal and the metal box should not be less than 5 × 103M Ω.
(2) Contact resistance of junction box
① Under the standard atmospheric conditions of the experiment, the contact resistance between the wire and the terminal block should not exceed 5 × 10-3 Ω.
② After the condition test, the increase in contact resistance between the wire and the terminal block should not exceed 3 × 10-3 Ω.
(3) Electrical strength
① Under the standard atmospheric conditions of the experiment, when subjected to an effective AC value of 500V between any two terminals and between any terminal and the metal box, there should be no breakdown or arcing phenomenon within 1 minute.
② After the condition test, there should be no breakdown or arcing phenomenon within 30 seconds when subjected to an effective AC value of 500V between any two terminals or between any terminal and the metal box.
2. Physical properties of junction box
(1) The plastic body of indoor junction boxes and various splicing devices should be made of flame-retardant materials.
(2) The box cover should be flexible to open, and the opening angle should not be less than 100 ° to ensure that it does not affect the splicing operation.
(3) The installation feet of the hanging junction box should have sufficient impact resistance strength.
(4) When the box cover is in the closed state, its sealing performance should meet the requirements of IP43 specified in GB2408.
(5) The soldering part of the terminal block should be evenly tinned, and its length should not be less than 5mm.
