Lower the assessed electrical capability of

• Lower the grade of
• Lower the electrical capacity of
• Lower the charges on
• Place less value on
• Downgrade, as electrical units
• Reduce taxes, in Britain
• Lower the value of

Wiktionary Word definitions in Wiktionary
vb. To lower the rated capability of any rated equipment or material.

WordNet Word definitions in WordNet
v. lower the rated electrical capability of electrical apparatus