Please see: ## If you are asking for help about a Project in: [https://easyeda.com/forum/topic/How-to-ask-for-help-and-get-an-answer-71b17a40d15442349eaecbfae083e46a](https://easyeda.com/forum/topic/How-to-ask-for-help-and-get-an-answer-71b17a40d15442349eaecbfae083e46a) You need to give more information about your application. Please post a link to the relay datasheet and at least give enough of your circuit to be clear about how you are driving the uln2003a or the optocoupler. Better would be to make your project public and post the link to it.

A short schematic of your relay circuit could help but, if you are referring to the coil voltage, the ULN2003 does not go that high. Furthermore, if your voltage reference is to the relay contact rating, the voltage isolation between coil and contacts required is normally handled by the relay itself and information is carried in the relay datasheet. Sorry if I misunderstood.you.