Test Engineering Laboratory
Test Report: BLE 11091
Date: July 31, 2012
6” Imperial Galvanized Steel Cable
Ladder Horizontal Bend Load and
Deflection Test
Report from a laboratory experiment conducted to measure cable ladder fitting load and
deflection performance
Cooper B-Line
509 West Monroe Street
Highland, IL 62249 USA
Steel Cable Ladder Horizontal Bend Fitting Load Test
Report # BLE 11090
Date: July 2012
Abstract:
The International Electrotechnical Commission (IEC) published a document in 2006
named International Standard 61537 - Cable management –Cable tray systems and
cable ladder systems. This publication specifies requirements and tests for cable tray
systems and cable ladder systems intended for the support and accommodation of
cables and possibly other electrical equipment in electrical and/or communication
system installations.
In Section 10.7.1 of IEC 61537, a test procedure is highlighted for verifying the
declared safe working load (SWL) of 90º horizontal cable ladder bend fittings. The
procedure is designed to test unsupported fittings. This IEC procedure was used as the
basis for test design.
Additionally, the National Electrical Manufacturers Association (NEMA) published
a document in 2006 named VE 2-2006, Cable Tray Installation Guidelines. This
publication is a guide for the proper shipping, handling, storing, installing, and
maintaining of cable tray systems.
VE 2-2006 discusses the recommended support locations for cable ladder
system horizontal bend fittings and attached cable ladder sections. However, the
document allows for variations to this guidance if the manufacturer offers an alternative
recommendation.
Cooper B-Line Engineering felt that the VE 2-2006 recommendations were
excessive based on the designs of B-Line cable ladder, fittings and splice plates. We
felt that designers could increase the range of supports needed under the cable ladder
attached to each fitting opening by up to three meters if a support was maintained for
the fitting. This scenario is not addressed in the IEC 61537 test procedure.
A test fixture was assembled to support a test sample consisting of a horizontal
bend fitting connected to two straight cable ladder sections. A configuration to test both
a supported fitting and an unsupported fitting was set up as well. The fitting was
subjected to a comprehensive load test battery where deflection was measured and the
test sample was inspected for any damage.
Based on the results of the test, Cooper B-Line’s 90 degree imperial cable ladder
fittings safely support a load of 275 kg/m (185 lbs/ft) in galvanized steel in both an
unsupported configuration and a supported configuration as described in this test report.
Further, Cooper B-Line cable ladder allows for a wider range of support placement
locations under the attached cable ladder as compared to the NEMA VE 2-2006
standard when a support is provided for the 90º bend fitting.
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Steel Cable Ladder Horizontal Bend Fitting Load Test
Report # BLE 11090
Date: July 2012
Table of Contents
Abstract: .......................................................................................................................................... i
Table of Contents ......................................................................................................................... ii
1. Introduction, Background and Theory ............................................................................... 1
2. Description of Test Setup .................................................................................................... 2
3. List of Equipment Used ........................................................................................................ 3
4. Procedure ............................................................................................................................... 3
5. Data ......................................................................................................................................... 5
6. Analysis of Data .................................................................................................................... 6
7. Discussion of Results ........................................................................................................... 7
8. Conclusions ........................................................................................................................... 7
9. References ............................................................................................................................. 7
10. Appendix ............................................................................................................................. 8
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Steel Cable Ladder Horizontal Bend Fitting Load Test
Report # BLE 11090
Date: July 2012
1. Introduction, Background and Theory
In 2006, The International Electrotechnical Commission (IEC) published a the
second edition of a document named International Standard 61537 - Cable
management –Cable tray systems and cable ladder systems. This publication specifies
requirements and tests for cable tray systems and cable ladder systems intended for
the support and accommodation of cables and possibly other electrical equipment in
electrical and/or communication system installations.
In Section 10.7.1 of IEC 61537, a test procedure is highlighted for verifying the
manufacturer’s declared safe working load (SWL) of 90º horizontal cable ladder bend
fittings. The procedure is designed to test unsupported fittings that are attached via
splice plates to cable ladder straight sections. This IEC procedure was used as the
basis for test design.
Additionally, the National Electrical Manufacturers Association (NEMA) published a
document in 2006 named VE 2-2006, Cable Tray Installation Guidelines. This
publication is a guide for communicating the proper shipping, handling, storing,
installing, and maintaining of cable ladder systems. Cable ladder system design must
comply with NEC Article 392, NEMA VE 1, and NEMA FG 1, and follow safe work
practices as described in NFPA 70E. VE 2-2006 helps in ensuring compliance to all
these standards. The guidelines in this publication are useful to engineers, contractors,
and maintenance personnel.
VE 2-2006 discusses the recommended support locations for cable ladder
system horizontal bend fittings and attached cable ladder sections. However, the
document allows for variations to this guidance if the manufacturer offers an alternative
recommendation.
Cooper B-Line Engineering felt that the VE 2-2006 recommendations were
excessive based on the designs of B-Line cable ladder, fittings and splice plates. We
felt that designers could increase the range of supports needed under the cable ladder
attached to each fitting opening by up to three meters if maintaining a support for the
fitting. This scenario is not addressed in the IEC 61537 test procedure.
On page 22 of VE 2-2006, Section 4.4.1 discusses the recommended support
locations for fittings. NEMA suggests placing supports under attached ladder sections
within 600 mm (24 inches) of each fitting extremity and another support at the mid-point
of the arc under the fitting itself. VE 2-2006 allows for variations to this guidance if the
manufacturer offers an alternative recommendation.
Cooper B-Line Engineering felt that these recommendations were excessive
based on the designs of B-Line cable ladder, fittings and splice plates. We felt that we
could either eliminate a support specifically for the fitting, or increase the range of
supports needed under the attached ladder sections at each fitting extremity from 600
mm up to the attached ladder’s half span (not to exceed 3000 mm) if a fitting support
was provided.
Two test fixtures were assembled for this test. One, to test Option #1 in SK-3425
Support Recommendations for Steel Cable Ladder Horizontal Bend Fittings, supported
a test sample consisting of a 90 degree horizontal bend with a single support
underneath and connected to two straight cable ladder sections supported at 3000 mm
Test Engineering Laboratory
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Steel Cable Ladder Horizontal Bend Fitting Load Test
Report # BLE 11090
Date: July 2012
(118 in) from the fitting splices. The second test fixture, to test Option #2 in SK-3425,
supported a test sample consisting of a 90 degree horizontal bend with a single
unsupported fitting connected to two straight cable ladder sections supported at 600
mm (24 in) from the fitting splices. The fittings were loaded with weights up to 275 kg/m
(185 lbs/ft). After each incremental load was applied and the described soak time was
reached, the deflection of the fitting was measured. Following the measurement, visual
inspection was performed to ensure no damage to the test sample occurred during the
load.
2. Description of Test Setup
Figure 1 - Test Setup for Option 1 and Option 2
Option #1 - The test set-up consisted of a cable ladder test assembly (90 degree
horizontal bend, two straight cable ladder sections, and four splice plates) supported by
three support structures placed as shown in Figure 1. Steel bars were evenly loaded
onto the bend fitting in a quantity that provided the desired test loads along with a
counterbalance weight equaling one half of the test load on the opposite side of each
attached straight section.
Test Engineering Laboratory
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Steel Cable Ladder Horizontal Bend Fitting Load Test
Report # BLE 11090
Date: July 2012
Option #2 - The test set-up consisted of a cable ladder test assembly (90 degree
horizontal bend, two straight cable ladder sections, and four splice plates) supported by
four support structures placed as shown in Figure 1. Steel bars were evenly loaded onto
the test sample in a quantity that provided the desired test loads along with a
counterbalance weight equaling one half of the test load on the opposite side of each
attached straight section.
3. List of Equipment Used
Option 1 Test Set-Up: Each Option #1 test sample consisted of:
•
One 6G-36-90HB36 galvanized steel 6” high x 36” wide, 36” radius, 90 degree
horizontal bend fitting
•
Two 464G12-36-240 galvanized steel 6” high x 36” wide x 240” long cable ladder
straight sections
•
Four 9G-8006 galvanized steel splice plates with standard 3/8” attachment
hardware (carriage bolts and serrated flange nuts)
Each test sample was support by a test fixture including:
•
Four or five 36” high metal workhorses with a 1.75” support surface
•
Two calibrated dial gauges
•
Rectangular steel strips each weighing 5 pounds (2.3kg)
4. Procedure
Support options #1 and #2 from Figure 1 was performed on galvanized steel test
samples.
The test procedure for support option #1 was performed as follows:
1. The test sample was assembled to standard work instructions per Cooper B-Line
catalog number CT-10. The straight sections were attached to either side of the
horizontal bend using a splice plate and hardware, and all hardware was
tightened to 27 foot-pounds of torque.
2. A test fixture consisting of three support workhorses was set up per Figure 1 with
a single support beneath the center of the horizontal bend fitting, mid-arch, at a
45o angle respective to the straight sections and contacting both rails of the
horizontal bend, and a support under each attached cable ladder section 3000
mm from the fitting splice.
3. The test sample was installed on the test fixture and counter balance weights
were installed at the ends of the straight ladder sections at the farthest point from
the fitting.
4. The test sample was leveled and two dial gauges were placed contacting each
rails of a single straight section, midway between the straight section support and
the fitting support. This distance is approximately 2080mm from either support.at
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Steel Cable Ladder Horizontal Bend Fitting Load Test
Report # BLE 11090
Date: July 2012
the midpoint of the cable ladder’s inside rail (Point A) and outside rail (Point B),
where the gauges were to set to record the zero-load dial position from which
deflection distance would be measured.
5. The test sample was loaded evenly with steel strips representing a load of
44.6kg/m (30 lbs/ft).
6. The test sample was subjected to that load for a period of approximately five
minutes, and then a measurement was taken at Points A and Point B to measure
the deflection. The test sample was also visually inspected for any damage.
7. The test sample was loaded with an incremental 44.6kg/m (30 lbs/ft) for a total
load of 89.3 kg/m (60 lbs/ft).
8. The test sample was subjected to that load for a period of minutes, and then a
measurement was taken at Point A and Point B to measure the deflection. The
test sample was also visually inspected for any damage.
9. Steps 7 and 8 were repeated in increments of 44.6kg/m (30 lbs/ft) per trial for a
total of 133.9, 223.2, 267.9, 276.8, and 303.6 kg/m (90,150, 180, 186, and 204
lbs/ft), the stopping point determined by either test sample failure or excessive
deflection.
10. The weights were removed and the test sample was visually inspected then
disassembled for further inspection.
The test procedure for option #2 was performed as follows:
1. The test sample was assembled to standard work instructions per Cooper B-Line
catalog number CT-10. The straight sections were attached to either side of the
horizontal bend using a splice plate and hardware, and all hardware was
tightened to 27 foot-pounds of torque.
2. A test fixture consisting of four support workhorses was set up per Figure 1 with
a support under each attached cable ladder section placed 600 mm from the
fitting splice and a support at the far end of the attached cable ladder straight
sections.
3. The test sample was installed on the test fixture and counter balance weights
were installed at the ends of the straight ladder sections at the farthest point from
the fitting.
4. The test sample was leveled and two dial gauges were placed at the midpoint of
the fitting’s inside rail (Point A) and outside rail (Point B) to set and record the
zero-load dial position from which deflection distance would be measured.
5. The test sample was loaded evenly with steel strips representing a load of 200
pounds or 26.3 lbs/ft (39.1 kg/m).
6. The test sample was subjected to that load for a period of approximately five
minutes, and then readings were taken at Points A and B to measure the
deflection. The test sample was also visually inspected for any damage.
7. The test sample was loaded with an incremental 200 pounds yielding a test
sample load of 52.9 lbs/ft (78.7 kg/m).
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Steel Cable Ladder Horizontal Bend Fitting Load Test
Report # BLE 11090
Date: July 2012
8. The test sample was subjected to that load for a period of approximately five
minutes, and then a measurement was taken at Points A and B to measure the
deflection. The test sample was also visually inspected for any damage.
9. Steps 7 and 8 were repeated in for loads of 79.3, 105.7, 132.1, 158.5, 185.0,
211.4, 237.8, 264.2, 290.7 and 303.9 lbs/ft. (118.0, 157.3, 196.6, 235.9, 275.3,
314.6, 353.9, 393.2, 432.6 and 452.3 kg/m), the stopping point determined by
either test sample failure or excessive deflection.
10. The weights were removed and the test sample was visually inspected then
disassembled for further inspection.
5. Data
6” Galvanized Steel – Option #1
Load (lbs/ft)
Average
Deflection
(in)
Deflection
1(in)
Deflection 2
(in)
0
0.000
3.832
3.627
30
0.285
3.524
3.365
60
0.374
3.459
3.252
90
0.561
3.389
2.948
120
0.706
3.322
2.726
150
0.873
3.280
2.434
180
1.150
3.201
1.959
186
1.233
3.116
1.878
204
1.641
2.960
1.217
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Notes
Failure due to excessive
deflection
Steel Cable Ladder Horizontal Bend Fitting Load Test
Report # BLE 11090
Date: July 2012
6” Galvanized Steel – Option #2
Load
(lbs/ft)
Average
Deflection
(in)
Deflection
1(in)
Deflection
2 (in)
Total Load
(lb.)
0.00
0.059
3.929
3.300
0
26.42
0.117
3.924
3.187
200
52.85
0.181
3.905
3.091
400
79.27
0.194
3.889
2.978
600
105.69
0.334
3.964
2.877
800
132.12
0.414
3.805
2.757
1000
158.54
0.484
3.753
2.649
1200
184.96
0.547
3.752
2.510
1400
211.39
0.626
3.741
2.394
1600
237.81
0.747
3.736
2.242
1800
264.24
0.864
3.657
2.078
2000
290.66
0.933
3.569
1.932
2200
303.87
0.974
3.525
1.838
2300
Notes
Failure due to
excessive
deflection
6. Analysis of Data
Galvanized Steel – Option #1
This test was to verify that the recommended fitting support locations shown on
SK-3425 supported our stated SWL in compliance with IEC standards. Target load for
this test was 275 kg/m (185 lbs/ft) which was derived from the experimentally
determined failure load of the 464G12-36-240 straight section, which was tested to the
IEC standards, and was found to have a deflection failure load of 275 kg/m (210 lbs/ft).
Cooper B-Line expected that the deflection at the stated loads would not exceed
42.0 mm (1.654 in) per the IEC standard definition of failure at 1% deflection of the mid
line length of the fitting, which was 4201 mm (90.8 in). The target load was reached
prior to deflection failure, so our support recommendation was demonstrated to meet
IEC standards.
A visual inspection of the test assembly during the test as well as the test assembly
components following the test showed no damage from the test
Test Engineering Laboratory
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Steel Cable Ladder Horizontal Bend Fitting Load Test
Report # BLE 11090
Date: July 2012
Galvanized Steel – Option #2
This test was to verify that the recommended fitting support locations shown on
SK-3425 supported our stated SWL in compliance with IEC standards. Target load for
this test was 275 kg/m (185 lbs/ft) which was derived from the experimentally
determined failure load of the 464G12-36-240 straight section, which was tested to the
IEC standards, and was found to have a deflection failure load of 275 kg/m (210 lbs/ft).
Cooper B-Line expected that the deflection at the stated loads would not exceed
42.0 mm (1.654 in) per the IEC standard definition of failure at 1% deflection of the mid
line length of the fitting, which was 4201 mm (90.8 in). The target load was reached
prior to deflection failure, so our support recommendation was demonstrated to meet
IEC standards.
A visual inspection of the test assembly during the test as well as the test assembly
components following the test showed no damage from the test
7. Discussion of Results
The test fixture and test sample was set up to as closely replicate an actual
installation as could be replicated in a test laboratory. The only deviation from a “realworld” replication was using steel strips in place of actual power cabling as the system
load. However, this was a highly accurate procedure for replicating cable ladder system
load stresses.
The test galvanized steel samples behaved as expected. The target load ratings
were set from published load ratings of Cooper B-Line straight cable ladder sections.
There were no observations of unexpected behavior in the test samples during
the execution of the testing.
8. Conclusions
Cooper B-Line’s horizontal bend fitting support recommendations made in SK-3425
meet our declared safe working load requirements as verified by the IEC 61537:2006
test procedure. Further, either Cooper B-Line’s Option #1 or Option #2 support
recommendations made in SK-3425 can be used in favor of the support
recommendations made in NEMA VE 2-2006.
9. References
Cooper B-Line, Inc. CT-10 Cable Tray Systems. Highland, IL: Cooper B-Line, Inc.,
2010.
Cooper B-Line, Inc. SK-3425 Recommended Support Locations for Steel Ladder
Horizontal Bend Fittings: Cooper B-Line, Inc., 2012.
International Electrotechnical Commission. IEC 61537:2006 - Cable management –
Cable tray systems and cable ladder system. Geneva, Switzerland: International
Electrotechnical Commission, 2006.
Test Engineering Laboratory
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Steel Cable Ladder Horizontal Bend Fitting Load Test
Report # BLE 11090
Date: July 2012
National Electrical Manufacturers Association. NEMA Standards Publication VE 2-2006
Cable Tray Installation Guidelines. Rosslyn, VA: National Electrical Manufacturers
Association, 2006.
10. Appendix
Figure 2 - Photograph of Option #1 Test Sample and Test Fixture
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Steel Cable Ladder Horizontal Bend Fitting Load Test
Report # BLE 11090
Date: July 2012
Figure 3 - SK3425-A Recommended Support Locations Drawing
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