Minimum box length must be at least 8 × the largest conductor diameter. Conduit must have proper fittings. The introduction of maintenance free junction boxes was a small change made in the last Amendment but it is likely to have the most practical results. Item (vi) was added to regulation 526. What Is NOT Allowed: What IS Usually. The Maintenance Free junction box provides a secure and maintenance free means of connecting ixed wiring in any indoor application, whether it be under loor situations, between ground and irst loor in houses, or where jointing of cables is used to aid rewiring. You need to calculate and select the right number and spacing of cables when using junction boxes. This step keeps your project safe and. flex is not enclosed. This is due to the junction box connection method not facilitating an easy means of enclosing the outer sheath, a non-complianc ithin the junction box.