Just a few last words on vents…
The vent holes need to have a total area large enough to give the desired flow rate. The temptation is always to stack holes (or slots) as close together as possible, but the strength of the panel or product case can be reduced condiderably. There’s a trade off, as usual. More stiffness can be introduced by uing louvers if the case is sheet metal (microwave ovens, clothing lockers etc) but the appearance needs careful thought.
Europe and the USA use different standards for ingress protection. In Europe/UK, the relevant standard is EN60529 (classifies degrees of protection provided by enclosures, in other words the ‘IP’ rating). In the US, the standard is NEMA 250. Note that these standards describe how well the enclosed equipment is protected, they are not user safety standards.
As a general guide, inquisitive fingers can be denied access by a hole of not more than 7.5mm diameter (or 3.5mm diameter for infants and children).
If you can’t find the data,visit design-bites.com. NEMA and IP rating tables are in a booklet entitled Design Directions. Access hole sizes are in the booklet ‘Human Factors and Aesthetics’. They’re downloadable if you have a PayPal account (or a credit card).