HMRC Admin 10 Response

Hi Peter Morris
If another electrician is fitting the second electrical consumer unit then this in itself is not an enery saving material and so the electrician would need to charge 20% for this supply.
Thankyou.

Hi I Ahmad
Please see the CWG2 section 4.6.6 :
2023 to 2024: Employer further guide to PAYE and National Insurance contributions
If an employee meets those criteria then there is not liability for tax or NI.
Thankyou.

Hi MAF-UK
We cannot advise why tax codes have changed as these are issued by personal tax, your employees will need to contact personal tax to enquire. 
Thankyou.