Specifications

Chapter 4: Environmental Considerations
Lightning and Surge Protection
(12/99) 4-11
• Protect cables by placing them in conduit or teflon wrap.
• Locate tanks (and weigh modules) away from corrosive materials and chemicals.
The combined effects of temperature, water, and air can corrode nearby weigh
modules. If tanks are near corrosive substances, provide protective coatings and
shieldings. Positive air flow in the area can also help prevent corrosion damage.
• Store tools, supplies, and trash away from the tank and weighing system.
NEMA/IP classifications for electrical equipment enclosures are covered in Appendix 10.
A chemical resistance chart is provided in Appendix 12.
Lightning and Surge
Protection
Lightning protection devices should be installed to protect a scale from being damaged
by lightning. Use devices that are designed to keep the current produced by lightning
from reaching ground through the load cell. Instead, the devices should provide a low-
resistance alternative path to ground near each weigh module (see Figure 4-6).
• Verify the integrity of any existing grounding systems.
• Use a single-point grounding system.
Ground Strap
Ground Rod
Figure 4-6: Grounding System for a Weigh Module
Surges are brief changes in voltage or current. They can be caused by lightning or by
equipment with large motor loads (HVAC systems, variable-speed motors, etc.). Minor
power surges can be eliminated by using an Uninterruptable Power Supply (UPS) or
Power Conditioner. You should provide surge protection to prevent damage to a weigh
module system.