When you have completed work on the electrical equipment that has had an Arc Flash Hazard Analysis completed on it. Do you supply the customer with any documenation that this work may or may not affect the current Arc Flash rating of their electrical equipment? In 70E it states that the analysis must updated if they make any modifactions.

Never thought about it. Perhaps (but I'm not a lawyer) the burden would be on the owner to keep track of changes but in the crazy litigation environment that we have (U.S.) it might not be a bad idea. Then on the other hand, would providing the information to the owner shift the burden to you in the event something goes wrong? I'm not sure what a good answer would be but it is a great question.

The customer is ultimately responsible for posting accurate information at his own facility

If your work could increase the arc hazard, then you should advise the customer that it could. Unless your contract scope of work includes arc hazard studies, you are not obligated to perform one. If you are in the business of performing arc hazard studies, this could be a source of new business.

I work in an engineering field services organization and our quotes for some types of work include a statement that power system studies or similar evaluation are specifically not included in the scope of work and an evaluation of whether system studies are required has not been conducted. Our field engineers also notify the customer if they perform work that could affect posted study results. I'm not sure how many customers actually hear what they are being told and take any actions to verify or update their study.

For the customers who have us maintain their study and perform field work this isn't an issue - I work with the field engineers to ensure that protective device changes are engineered before they are put into place, and that any changes found in the field are communicated back to me and I update the model and labels accordingly.