The helpline/mailbox can only help with issues to do with electrical installation work.
The technical helpline
The telephone service typically operates on the following days and times:
T: +44 (0)1438 765599
F: +44 (0)1438 765526
Monday and Friday, from 9 am to 12 pm and 2 pm to 4:30 pm.
(Days subject to change - please listen to the recorded message)
Disclaimer: While the IET believes that the information and guidance provided over the helpline is correct, parties must rely upon their skill and judgement when making use of them. The IET assumes no liability for loss or damage caused by error or omission, whether such an error or omission is the result of negligence or any other cause. Where reference is made to legislation it is not to be considered as legal advice. Any and all such liability is disclaimed.
Have you tried the online forum?
The Wiring and the Regulations BS 7671 forum is a great place for peer-to-peer support from experienced engineers and technicians. If you're looking for a quick opinion or shared experience, ask in the forum.