Nema 1 standard Cable Tray and ladder Application information world wide standard in cable supports best practise
NEMA 1 – NEMA STANDARD CABLE TRAY & LADDER
Extract from NEMA Publication
Section 3 Performance Standards and Load/span Class Designations
3.1 Working (Allowable) Load Capacity
The working (Allowable) load capacity represents the ability of the cable tray to support the static weight of cables. It is the equivalent, to the destruction load capacity as determined by testing in accordance with 4.1 divided by a safety factor of 1.5
Nema Standard 3-14-1979
3.2 Load/Span Class Designations
There shall be three working load categories of cable tray
- 50lbs/liner ft- (74.4Kg/m) (Symbol A)
- 75lbs/liner ft- (116.6Kg/m) (Symbol B)
- 100lbs/liner ft- (148.8.Kg/m) (Symbol B)
And four support span categories of
- 8 feet (2.44m)
- 12 feet (3.66m)
- 16 feet (4.87m)
- 20 feet (6.10m)
Utilising these, load/span class designations of table 3-1 shall apply.
Nema Standard 3-14-1979
TABLE 3-1
Load/Span Class Designations
|
Working Lb./ft.
|
Load (kg/m)
|
Support Feet
|
Span(m)
|
Class Designation 3.1
|
|
|
|
|
|
|
|
50
|
(74.4)
|
8
|
(2.44)
|
8A
|
|
75
|
(111.6)
|
8
|
(2.44)
|
8B
|
|
100
|
(148.8)
|
8
|
(2.44)
|
8C
|
|
|
|
|
|
|
|
50
|
(74.4)
|
12
|
(3.66)
|
12A
|
|
75
|
(111.6)
|
12
|
(3.66)
|
12B
|
|
100
|
(148.8)
|
12
|
(3.66)
|
12C
|
|
|
|
|
|
|
|
50
|
(74.4)
|
16
|
(4.87)
|
16A
|
|
75
|
(111.6)
|
16
|
(4.87)
|
16B
|
|
100
|
(148.15)
|
16
|
(4.87)
|
16C
|
|
|
|
|
|
|
|
50
|
(74.4)
|
20
|
(6.10)
|
20A
|
|
75
|
(111.6)
|
20
|
(6.10)
|
20B
|
|
100
|
(146.8)
|
20
|
(6.10)
|
20C
|
Note: The above working loads are for cable only ; when considering applications requiring concentrated loads, see 6.2 Note 2: These designations do not apply to channel tray please consulte that manufacture
