A technique for resolving a violation of an investment account restriction is provided. The box is installed on a floor in a vehicle interior. The liquidus temperature T1L of the first joiner solder is less than a solidus temperature TCS of the core solder. This method makes it possible to overcome the problem of the presence of tin in the first washing bath supplied with water by a counter-current coming from the reversal bath. Preferably, the optical splitter is tuneable to direct at least part of the optical power from the optical source to each of the first and second paths, in varying proportions.