Gives the requirements for three types of sleeving constructed from polyethylene terephthalate yarns using either braided or knitted construction, with a continuous acrylic based coating and differentiated by their breakdown voltage: high breakdown voltage (sheet 420), medium breakdown voltage (sheet 421) and low breakdown voltage (sheet 422). Experience of product performance indicates that sleeving of the types specified in these sheets may be suitable for operation at 130 °C or in some applications at temperatures up to 155 °C.