Elbow and parkingstand arresters are provided with a ground wire as well as a grounding eye for attaching a No.14 or equivalent drain wire. It is important to understand the correct way to install the drain wire, so that it does not negatively impact the performance of the arrester.
The drain wire must remain attached to the arrester after a venting event. This allows the arrester housing to remain grounded even if the MOV block stack has been ejected. With the drain wire attached to the ground braid (Figure 1), the force of the block stack exiting during an event may rip the drain wire off the grounding eye, causing the arrester housing to be ungrounded and possibly energized.
Another reason to not attach the drain wire to the ground braid is, if the arrester were to vent, the drain wire being wrapped around the grounding braid might prevent the arrester block stack from fully exiting the arrester housing. This may cause the arrester to lock out the line since the fault may not clear. Hubbell elbow arresters are designed to meet all safe failure requirements of IEEE C62.11, minimizing the chance of damage to the equipment or worse, personal injury.
Please keep these things in mind when attaching the drain wire to elbow and parkingstand arresters.
Figure 1 (left): Incorrect Installation
Figure 2 (right): Correct Installation