How to choose wire and cable for explosion-proof distribution box (control box)

a. Wire and cable symbol meaning:

Model Meaning [1]-[2][3][4][5][6][7][8]-[9]

[1]ZR-flame retardant, NH-refractory, ZA(IA)-intrinsically safe (R: cord)

[2] Use. Power cable default representation, K-control cable, P-signal cable, DJ-computer cable

[3] Insulation layer. V-polyvinyl chloride, Y-polyethylene, YJ-crosslinked polyethylene, X-rubber, Z-paper

[4] Conductor. The T-copper core defaults to the L-aluminum core.

[5] inner sheath (sheath), V-polyvinyl chloride, Y-polyethylene, Q-lead bag, L-aluminum bag, H-rubber, HF-non-combustible rubber, LW-wrinkled aluminum sleeve, F - Neoprene, N-butyl rubber jacket.

[6] Features. The package type does not need to be indicated, F-phase separation lead pack phase separation jacket, D-no drop oil, CY-oil filling, P-shield, C-filter, Z-DC.

[7] Armored layer. 0-None, 2-double steel strip (24-steel strip, thick round steel wire), 3-fine round steel wire, 4-thick round steel wire (44-double thick round steel wire).

[8] The outer layer. 0-none, 1-fiber layer, 2-polyvinyl chloride sheath, 3-polyethylene sheath.

[9] Rated voltage. Expressed in numbers, kV.

Example: RV300/500V copper core PVC insulated flexible conductor;

a. selecting a conductor cross section according to the magnitude of the main circuit current;

b. Determine the number of main loop phases (3+1 or 4+1);

c. Determine the insulation of the wire and cable (polyethylene, rubber, etc.);

d. Find the outer diameter of the wire and cable according to the wire and cable selection sample;

e. According to the outer diameter of the wire and cable, select the incoming line, or the outlet end, seal ring, gasket, sealing piece and other parts;

Example: Main circuit three-phase circuit breaker 250A, from the table 6 to find the conductor cross section 95mm2, select 3+1 type wire

Cable, ie: 3×95+1×50 cable approximate outer diameter 39.5mm (through diameter 40)

It can choose G11/2 head, compression nut, sealing ring, washer and other outlet and inlet components.

f. The same method can also calculate the branch circuit;