Hi The isolation of the bypass in the yard should be done in (inside) the luminaire above the floor level, in that case it is not critical since you should not deal with extreme humidity or water; The joint must be neat and you can use self-vulcanizing 3M tape next to common tape interleaved. In the case that you cannot do the above, I recommend that you make a joint for a wet area or with water, of the "bottle" type, or simply with safe isolation techniques; I would never place a box that probably accumulates water and is probably not airtight. With safe insulation technique, I mean layer on layer of common insulating tape and self-insulating insulating tape while finishing the curb ends on a single cable, never two together; this type of splices , maybe something improved with thick-walled spaghetti I have used in pumps submerged in water, so it may well be on land, but remember that if you use a box and Water is introduced, the remedy is worse than the disease. Greetings to all