Employees cannot claim expenses where there is a 'dual use' - ie some personal use. This is because employee expense claims must be 'wholly exclusively and necessarily' business related.
Note there is no problem if the business buys and owns equipment and an employee makes an insignificant amount of personal use.
When you rent your own equipment to your limited company the business is only paying for the business use. However you are receiving income.
Initially this income is offset by tax relief on the asset you are renting out. It is important not to rent the same piece of equipment to your business for longer than it takes to recover its cost, as after that you will be making a taxable profit that will need to be declared on your self assessment return.
Eg: If you think the equipment will be used for say 2.5 years (30 months) then charge no more than three and a third percent per month in rental.