Modern energy meters characterises very low burden of measuring inputs. On the other hand current or voltage transformer works properly if its secondary winding burden lays between 25 - 100% of its rated output. In case of old type transformers the situation of not enough burden can occur. Load resistors RDZ-3 are installed in order to add extra load of secondary winding of current or voltage transformer. The RDZ-3 resistors can be also applied in order to eliminate ferro-resonance phenomena. RDZ-3 resistors are able to work in outdoor metering cabinets of ingress protection degree min. IP 40.