1.The following distribution systems are allowed for direct current and single-phase alternating current:
(a)two-conductor systems of which one is earthed (L1/N/PE);
(b)single-conductor systems using the hull return principle, only for local installations (for example, starting gear for combustion engines, cathodic protection) (L1/PEN);
(c)two-conductor systems that are insulated from the hull (L1/L2/PE).
2.The following distribution systems are allowed for three-phase alternating current:
(a)four-conductor systems with earthing of the neutral point, not using the hull return principle (L1/L2/L3/N/PE) = (network TN-S) or (network TT);
(b)three-conductor systems insulated from the hull (Ll/L2/L3/PE) = (network IT);
(c)three-conductor systems with earthing of the neutral point using the hull return principle, however, that shall not be allowed for terminal circuits (L1/L2/L3/PEN).
3.The inspection body may allow the use of other systems.