The service supplying power to a small industrial facility will consist of four disconnect switches. The disconnect switches will be separate enclosures with a main service disconnecting means in each enclosure. Each disconnect switch will be rated 225 amperes and the ungrounded service conductors supplying power to each disconnect switch will be 4/0 copper. A common grounding electrode conductor will be installed and a grounding electrode conductor tap will be installed from each disconnect switch to the common grounding electrode conductor. What size grounding electrode conductor tap is required from each disconnect switch to the common grounding electrode conductor?