The IVA manual makes it clear in section 69 that vehicles must comply with R100. This is not true. If the electric vehicle is under 48 volts then it will be accepted for IVA without proof of compliance with R100.
Confirmation email copied below from DVSA.
16:31 (16 minutes ago)
Good Afternoon Stuart,
Compliance to ECE Reg 100.01 Electrical Safety is required for Basic IVA if the operating voltage is more than 48 volts.
All Normal IVA applications will require compliance to ECE Reg 100.01 Electrical Safety.
For example someone who has built a kit car and applies in the Amateur Built test class and the operational voltage is not more than 48 volts then no evidence of Electrical Safety required, a visual inspection as per section 69 of the inspection manual would be carried out.