Electrical work on industrial equipment

Tobster86

I'm hoping to find an electrical engineer here who may be able to provide a brief summary and save me sifting through mountains of rules & regulations to find a hopefully simple answer!

I work as an embedded software engineer for a company that manufactures machines for food production and now have enough experience to start exploring further career possibilities.

I've recently, through an old colleague who I worked in a pub with whilst studying, happened upon a possible project on the side whereby the company he works for want to add some controls & sensors to their production line. This will involve writing a program for a control module and wiring it into the system. It's too small a job for the company I work for to be interested, but potentially lucrative for me to take on myself. I'm prepairing to meet with their directors in the near future.

I believe I'm more than capable of doing the necessary wiring, but don't hold any electrical qualifications. As I would be going in as a freelance consultant we must assume the task would be unsupervised. What laws, rules & regulations are applicable with regards to who can perform wiring changes to industrial machinary? Are different rules applicable for different circuit voltages? I expect the circuitry to be 24VDC, but will out of common sense leave alone anything above and including mains.