Thread Data
Metric
standard thread conforming to EN60423Thread size | External thread outside diameter(mm) | Internal thread inside diameter(mm) | Pitch (mm) |
---|---|---|---|
M12 | 12.0 | 10.4 | 1.5 |
M16 | 16.0 | 14.4 | 1.5 |
M20 | 20.0 | 18.4 | 1.5 |
M25 | 25.0 | 23.4 | 1.5 |
M32 | 32.0 | 30.4 | 1.5 |
M40 | 40.0 | 38.4 | 1.5 |
M50 | 50.0 | 48.4 | 1.5 |
M63 | 63.0 | 61.4 | 1.5 |
M75 | 75.0 | 73.4 | 1.5 |
PF / gas
Japanese conduit thread conforming to JIS B 0202Thread size | External thread outside diameter(mm) | Internal thread inside diameter(mm) | Pitch (mm) |
---|---|---|---|
½ | 21.0 | 18.6 | 1.81 |
¾ | 26.4 | 24.1 | 1.81 |
1 | 33.3 | 30.3 | 2.31 |
1 ¼ | 41.9 | 39.0 | 2.31 |
1 ½ | 47.8 | 44.8 | 2.31 |
2 | 59.6 | 56.7 | 2.31 |
NPT
American taper pipe thread conforming to ANS/ASME B1.20.1 - 1983Thread size (inches) | External thread outside diameter (mm) | Pitch mm |
---|---|---|
3/8 | 16.7 | 1.14 |
½ | 21.0 | 1.81 |
¾ | 26.4 | 1.81 |
1 | 33.3 | 2.21 |
1 ¼ | 41.9 | 2.21 |
1 ½ | 47.8 | 2.21 |
2 | 59.6 | 2.21 |
PG
German standard thread conforming to DIN40430Thread size | External thread outside diameter(mm) | Internal thread inside diameter(mm) | Pitch (mm) |
---|---|---|---|
PG7 | 12.5 | 11.3 | 1.27 |
PG9 | 15.2 | 13.9 | 1.41 |
PG11 | 18.6 | 17.3 | 1.41 |
PG13.5 | 20.4 | 19.1 | 1.41 |
PG16 | 22.5 | 21.2 | 1.41 |
PG21 | 28.3 | 26.8 | 1.59 |
PG29 | 37.0 | 35.5 | 1.59 |
PG36 | 47.0 | 45.5 | 1.59 |
PG42 | 54.0 | 52.5 | 1.59 |
PG48 | 59.3 | 57.8 | 1.59 |
UNEF / UNS / UN
American unified thread conforming to BS1580 used on circular connectorsUNEF imperial sizes | Thread size (inches) | External thread outside diameter (mm) | Internal thread inside diameter (mm) | Pitch (mm) |
---|---|---|---|---|
24 | 5/8 | 15.9 | 14.7 | 1.06 |
20 | ¾ | 19.1 | 17.7 | 1.27 |
20 | 7/8 | 22.2 | 20.9 | 1.27 |
20 | 1 | 25.4 | 24.0 | 1.27 |
18 | 1 3/16 | 30.2 | 28.6 | 1.41 |
18 | 1 3/8 | 34.9 | 33.4 | 1.41 |
18 | 1 ¼ | 31.8 | 30.2 | 1.41 |
18 | 1 7/16 | 36.5 | 35.0 | 1.41 |
18 UNS | 1 ¾ | 44.5 | 42.9 | 1.41 |
18 UNS | 2 | 50.8 | 49.3 | 1.41 |
18 UN | 2 ¼ | 57.2 | 55.4 | 1.41 |
Cable carrying capacity
UK wiring regulations BS7671, recommend that the total cross sectional area of the sum of the individual cables should not exceed 40% of the cross sectional area of the conduit. The nominal cross sectional area of single-core, stranded, PVC insulated cables is provided as a guide only. Other cables may have different dimensions.Nominal conductor size | Nominal overall cross sectional area (mm2) |
---|---|
1.0 | 6.6 |
1.5 | 7.6 |
2.5 | 9.6 |
4.0 | 14.5 |
6.0 | 18.8 |
10.0 | 29.3 |
16.0 | 40.2 |
25.0 | 63.8 |
35.0 | 83.5 |
50.0 | 113.0 |
70.0 | 149.0 |
95.0 | 204.0 |
Example: is LTP20 suitable for five 4.0mm2 cables?
- The total cross sectional area of the conductors is 5 x 14.5mm2 = 73mm2
- The cross sectional area of LTP20 is 3.142 x [inside diameter/2]2 = 201mm2
- % of conduit cross sectional area 73/201 = 36%
This is less than 40%; therefore this conduit is suitable for this combination of cables.
UK wiring regulations
UK wiring regulations BS7671 prohibit the use of flexible or pliable conduit as an earthing conductor.
Where conduits of 40mm and above penetrate fire barriers in buildings the wiring regulations stipulate that internal seals should be used to maintain fire resistance.
To meet the UK wiring regulations conduit should be self extinguishing unless they are to be buried or contained in non combustible material e.g: concrete or plaster.
Please telephone the Flexicon hotline for further guidance.