12) Electrical work to an existing dwelling not undertaken by a registered domestic installer qualified to complete and provide BS 7671 installation, commissioning and testing certificates.*
12) Gwaith trydanol i annedd sy’n bodoli eisoes NAD yw'n cael ei gyflawni gan osodwr domestig cofrestredig sy'n gymwys i gyflawni a darparu gosodiadau BS 7671, tystysgrifau comisiynu a phrofi. *