It depends who told you that you have not got a negligence claim.
If you have been to see a personal injury lawyer and he said that then you probably dont have a case if not I would see one.
The employer has a duty of care to you whilst at work and he needs to fulfill that duty of care. If you are injured as an act of god and the employer has done everything possible to ensure you are reasonably safe then he may be in the clear. Otherwise you may have a case and will need a lawyer to sort out the facts.