We have a heatsink on our product made from EPP. The temperature of this heatsink will reach 100°C max but won't need to be touched to use the product. Unfortunately it's impossible to stick something on the EPP to warn the user. What can we do?
To provide a complete answer to your question specific details about the product construction and identification of the person(s) intended to use it e.g. ordinary, instructed, etc. is needed. Based on what was shared we offer the following general information.
For constructions where the surface can be touched when an ordinary person is directed to access an area, provide all requirements are met, the maximum temperature based on energy source classification TS1, TS2, TS3 are specified in Table 38. Additionally, in Table 38 (2nd Ed, footnote e; 3rd Ed, footnote c) there are directions on the use/placement of an instructional safeguard. If the application & construction support its use, for applications where the surface need not be touched to operate equipment, per the footnote the instructional safeguard may be placed near the hot part. Please consider submitting the inquiry directly to UL for review and assistance.