1. Industry Standards and Load Ratings of Enclosuresby
Oldcastle Enclosure Solutions Team
Presenter: Ravi Devalapura, Ph.D.
MAG Specification and Details Committee
Water /Sewer Working Group Meeting
Phoenix, March 15, 2016

2. Objectives
This presentation is designed to provide basic understanding on:
What type of loads act on an enclosures after installation
Different load ratings & standards used in the industry
How to choose applicable standards and load factors
(their words..)
This coarse is designed to provide basic understanding on:
What type of loads act on an enclosure after the installation and what factors of safeties involved
Different load ratings & standards used in the industry
How to test boxes for wheel loading and what factors of safety are involved
At the end of this coarse, you will understand why load ratings are important and how to use right box to right applications.
Intended audience include Sales, CSRs, Engg team, and anyone who wish to learn load ratings on enclosures.
(Jason’s words)
This coarse will provide a basic understanding on:
The effect of loads on enclosures
Safety factors involved
Load ratings
Industry standards
Testing loads on enclosures
Which enclosures to use for various applications

3. Units and Terminology PSI Pounds per square inch PSF
Pounds per square foot
PCF
Pounds per cubic foot
Design Load
Load at which product is repeatedly applied safely
Test Load
Load at which product is considered to have passed the test requirement
Operating an electric switch is like turning on a water faucet. Behind the faucet or switch there must be a source of water or electricity with something to transport it, and with a force to make it flow. In the case of water, the source is a reservoir or pumping station; the transportation is through pipes; and the force to make it flow is provided by a pump. For electricity, the source is the power generating station; current travels through electric conductors (wires); and the force to make it flow - voltage, measured in volts, is provided by a generator.
Resistance
- Dry skin has a fairly high resistance, but when moist, resistance drops radically, making it a ready conductor.
- Measured in ohms.
Use extra caution when working with electricity when water is present in the environment or on the skin. Pure water is a poor conductor, but small amounts of impurities, such as salt and acid (both are contained in perspiration), make it a ready conductor.
Yield
Point on a stress/strain curve where the applied load no longer increases as deflection continues
Ultimate Load
Point where increasing load results in exceeding elastic limit of a material
Factor of Safety
Ultimate load/design load. Typically a factor of is commonly used
Deflection
Compression or bending measured in inches

4. Loads and Load Types
Loads Enclosures are subjected to different loads during their service life. These loads come from pedestrian, vehicular traffic, soil pressure, surcharge, and fluid pressure. The forces acting on the walls and lid of enclosure vary depending on the magnitude and the relative location of the enclosure with load.

5. Loads and Load Types
There are different types of loads or pressures which act on the enclosure unit. Loads vary depending on enclosure location and what the enclosures are designed to withstand.
Structural
Environmental
Pedestrian loads
Vehicle loads
Soil pressure
Surcharge Pressure
Fluid pressure
Impact Loads
Chemical resistance
UV Testing
Moisture effect
Freeze and Thaw
Coefficient of Friction
Flammability test
Other…

6. Standards and Specifications
SCTE 77 Specific to enclosures used for holding equipment used for telecommunication and other low voltage apparatus.
SCTE
Society of Cable Telecommunications Engineers
WUC
Western Underground Committee
ASTM
American Society for Testing and Materials
AASHTO
American Association of State Highway and Transportation
WUC GUIDE Covers requirements to non-concrete materials and four specific sizes.
ASTM C857 Load ratings for precast concrete utility structures.

7. Standards and Specifications
AASHTO For highways and bridges with deliberate vehicular traffic
Telcordia GR-902-CORE Issue Used mainly by the Telecommunication industry and differs with SCTE 77 in many test procedures
SCTE
Society of Cable Telecommunications Engineers
WUC
Western Underground Committee
ASTM
American Society for Testing and Materials
AASHTO
American Association of State Highway and Transportation
Enclosure Manufacturers
Manufacturer Standards Enclosure manufacturers have developed specifications based on their proprietary design and experience

8. Industry Standards - SCTE 77 2013
Covers conformance tests and requirements for enclosures containing telecommunication and other low voltage apparatus
Environmental Tests and Structural Load Tests
Test method are well defined with test set up figures for different Tier ratings
Some tests referred to follow ASTM standards and others are covered with a test procedure
All load ratings and deflection limits are listed in Tables (shown)

9. Industry Standards - Western Underground Committee (WUC) Guide 3.6
Applicable to non-concrete materials (plastic, polymer concrete)
Only four common sizes are covered
Includes both structural and material requirements
Provisions are similar to SCTE 77 but with less clarity
Provides details on testing criteria
WUC Guide is a “Guide”… NOT a “Standard”

10. Industry Standards - ASTM C857 - 11
Standard Practice for Minimum Structural Loading for Underground Precast Concrete Utility Structures
Provides vehicle and pedestrian live and dead loads.
Covers how to calculate applicable loads, load distribution, and lateral pressures from soil.
Categorizes these minimum designs into designations as in Table below.

11. Industry Standards - AASHTO
American Association of State Highway & Transportation Officials
Very detailed document for designing bridges and highways
Developed by Departments of Transportation officials
Takes into consideration a moving vehicle so it’s also specific to enclosures that will be in major traffic areas.
Two main categories: “H” for two-axel trucks and “HS” for tractor trucks
Category: H
H10, H15, H20
Category: HS
HS10, HS15, HS20

12. Industry Standards – Telcordia GR-902-CORE Issue 2 2013
Allows both metallic and nonmetallic materials for the handholes
Load tests are divided in to four categories and are color coded.
Lateral load cycles varies with size and a long-term (90 days) test is included
Requires extensive material- specific tests to meet the requirements

13. Industry Standards – Manufacturer Standards
Each manufacturer has developed their own standards based on experience, design, and proven applications.
Larger players offer different products and load ratings based on the application
Some specifications are based on empirical designs and some are well engineered.
The product data sheets can be confusing with limited information
One need to understand the performance in detail before choosing the right solution
Manufacturer Specification

14. Load Rating Comparison Chart
Performance
Category
Gross Vehicle Weight (lb)
Max Wheel Load (lb)*
Design Load (lb)
Test Load (lb)
Specification
Load Classification
Light Duty / Pedestrian Only --
300 psf
2,000
3,000
ASTM C 857
SCTE 77
Telcordia GR-902
A-0.3 Walkways
Light Duty, Pedestrian
Category I, Light Duty
Medium Duty / Non-Deliberate (Incidental) Traffic
19,500
40,000
7,800
16,000
5,000
8,000
15,000
10,400
12,000
7,500
16,640
22,500
24,960
WUC Guide 3.6
ASTM C857
Tier 5
Tier 8
Category II, Medium Duty
A-8 (HS-10), Light Traffic
Tier 15
In Shoulder or sidewalks
A-12 (HS-15), Medium Traffic
Category III, Heavy Duty
Heavy Duty / Non-Deliberate (Incidental) Traffic
33,750
Tier 22
Category IV
Designated Roadway Traffic
72,000
20,800
33,280
36,400
AASHTO
A-16 (H-20)
HS-20
* Max wheel load = 40% of GVW

15. Final Review….
There are several industry standards and guidelines available for enclosures.
Load criteria and safety factors are not uniform between industry specifications.
There are no industry standards for water market applications. Most municipalities spec call for pedestrian to 20K max loading.
“H20” and “20K” do not represent equal performance.
WUC, Guide 3.6 specification applies to non-concrete enclosures.
Though some products are rated equal, there may be difference in how they were tested and what protocols used.