In a duplicate supply layout, the customer is supplied with electricity from two separate service drops connected to individual feeders.

In a duplicate supply layout, the customer is supplied with electricity from two separate service drops connected to individual feeders.

• A. True
• B. False
• C. Sometimes
• D. Not applicable

Answer: (B)

Duplicate supply means there are two independent sources available, but only one feeds the customer's installation at any given moment. A transfer device—manual or automatic—connects one source to the service while isolating the other to prevent backfeeding and fighting between sources. This keeps protection coordination intact and ensures lineworkers aren’t exposed to energized equipment from a second source. So even though there are two service points and two feeders available, the customer is not continuously supplied by both; the second feeder is kept de-energized until a switch transfers over.

Duplicate supply means there are two independent sources available, but only one feeds the customer's installation at any given moment. A transfer device—manual or automatic—connects one source to the service while isolating the other to prevent backfeeding and fighting between sources. This keeps protection coordination intact and ensures lineworkers aren’t exposed to energized equipment from a second source. So even though there are two service points and two feeders available, the customer is not continuously supplied by both; the second feeder is kept de-energized until a switch transfers over.