Which washers are specified for securing lines to grounding bars in the given setup?

• A. Both Flat and Lock
• B. Flat Washer
• C. Lock Washer
• D. No Washers

Answer: (A)

The main idea here is that securing a conductor to a grounding bar needs both dependable mechanical support and a resistance to loosening under conditions like vibration and thermal cycling. Using a flat washer together with a lock washer provides those two benefits in one assembly.

The flat washer spreads the load from the bolt head or nut over a larger area of the grounding bar. This protects the copper or alloy surface from damage, helps maintain an even clamping force, and ensures the surface stays flat for solid electrical contact.

The lock washer adds a bite or spring action that helps prevent the fastener from backing off. In a grounding system, any loosening can raise resistance at the connection, create heat, and compromise the low-impedance path to earth. The lock washer helps maintain a consistent, tight grip.

So, combining both washers ensures the connection stays tight and conductive over time, even in the presence of vibration and temperature changes.

Using only one type would miss one of these protections: a flat washer alone can loosen under vibration, and a lock washer alone can damage the surface or not distribute load effectively. Neither washer would be ideal by itself for a reliable grounding connection.