TTS 171 : PART 1: 2002 ANNEX E PRESENTER WINSTON THOMAS ELECTRICALINSPECTOR 1 ELECTRICAL INSPECTOR 1

MAXIMUM CONDUCTORS IN CONDUIT AND BOXES Objective Simple guide Calculation

Cont’d. Maximum number of cables Conduits Boxes

CONDUITS Electrical Metallic Tubing or E.M.T Steel heavy gauge conduit PVC conduit

Surroundings Ambient temperature Level of mechanical protection APPLICATION

CAPACITIES For the maximum capacities Reference to Annex E Relevant table

TABLES IN ANNEX E Four tables Maximum PVC insulated non sheathed cables Space factor of 40 %

Cont’d. Two 90 0 bends Additional bends Cables reduced

USE OF TABLES Calculate number of cables for circuit  Choose cable size in column  Use maximum number of cables column

Cont’d.  Choose value equal to or greater than number of cables  Go to corresponding column for conduit size

TABLE E 2a  Covers maximum capacities  Steel conduit and E.M.T PVC insulated non-sheathed single core cables

Cont’d. Same cross-sectional area Imperial, AWG or MCM and Metric sizes

Example A 115/230V single phase a.c circuit requiring 16mm 2 single core cables is to be run in an E.M.T conduit. To determine conduit size.

Calculate Number of cables. (3) Cable size column. (16mm 2 ) Maximum number cables column. (4) Corresponding conduit size of 27 mm or (1 in).

Table E 2b Covers maximum capacities.  Steel heavy gauge conduits.  PVC insulated cables of same cross-sectional area.

Example Using three 16mm 2 cables as in the previous example. Follow same steps. Conduit size approximately the same.(25mm)

Table E 2c Covers maximum capacities.  PVC conduits  PVC insulated cables of same cross-sectional area

Example Same circuit to be run in PVC conduit. A grounding conductor is now required. Number of cables. ( 4 )

Cont’d Maximum number of cables column. (5) Conduit size - 32mm

Table E1 New addition to code. Covers maximum capacities. All types of conduits.

Cont’d PVC insulated cables of different cross-sectional areas Conduit factor Conductor factor.

Four 2.5mm 2, four 4.0mm 2 and two 6.0mm 2 cables, are to be drawn into a conduit. Total conductor factor = Sum of cable conductor factors. Example

Cont’d. Conduit factor shall be equal to or greater than total conductor factor.

4 x 4.0mm 2 factor = 4 x 39 = x 6.0mm 2 factor = 2 x 50 = 100 Total 376 Conduit factor Conduit 27mm ( 1 in. ) 4 x 2.5mm 2 factor = 4 x 30 = 120

CAPACITIES OF BOXES Table E 3 New addition to code. Maximum capacities. Outlet and junction boxes

Sixteen 4.0mm 2 cables to be spliced in a box. Determine size of box. First go to column for 4.0mm cables. Example

Cont’d. Then to row where value is equal to or greater than sixteen. Then to box in corresponding row. (4 11/16 x 2 1/8)

THE END