The standard applies to the selection and erection of wiring systems. Wiring systems are assemblies made up of one or more insulated conductors, cables or busbars and the parts which secure their fixing and, if necessary, their mechanical protection. The standard contains, amongst others, requirements for types of wiring systems, selection and erection according to the environmental influences, cross-sections of conductors, voltage drop in consumer installations, electrical connections, selection and erection for limitation of fires, proximity to other technical installations, selection and erection with regard to maintenance, including cleaning. The following significant modifications have been made with respect to DIN VDE 0100-520 (VDE 0100-520):2003-06: clause 521 has been restructured; b) 521.4 contains minor modifications with respect to busbar trunking systems and powertrack systems; c) requirements for the selection and erection of electrical equipment in cavity walls from DIN VDE 0100-482 (VDE 0100-482):2003-06 have been added in 521.15; d) clause 525 contains modifications regarding the maximum permissible voltage drop between house infeed and consumables which shall not be higher than indicated in the corresponding annex; e) clause 526 contains minor modifications regarding electrical connections including additional exclusions for the testing of connections and additional notes; f) clause 528 contains additional requirements with respect to proximities of underground power cables and telecommunication cables; g) clause 529 contains minor modifications regarding the selection and erection of wiring systems with regard to maintenance, including cleaning; h) Table 52F has been transferred to Annex A (informative) and is now Table A.52.1; i) Table 52G has been deleted; j) Table 52H has been transferred to DIN VDE 0298-4 (VDE 0298-4):2013-06; k) Table 52J is contained in 524.1 as Table 52.2. The responsible committee is UK 221.2 "Schutz gegen thermische Auswirkungen/Sachschutz" ("Protection against thermal effects/Property protection") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.