installation errors. This gives both robustness against failure and a potential for danger. Safety tests are complex At least one author claims that testing ring circuits may take 5–6 times longer than testing radial circuits. The installation tests required for the safe operation of a ring circuit are more time-consuming than those for a radial circuit, and DIY installers or electricians qualified in other countries may not be familiar with them. Load balance required Regulation 433-02-04 of BS 7671 requires that the installed load must be distributed around the ring such that no part of the cable exceeds its rated capacity. In some cases this requirement is difficult to guarantee, and may be largely ignored in practice, as loads are often co-located (e.g., washing machine, tumble dryer, dish washer all next to kitchen sink) at a point not necessarily near the centre of the ring. However, the fact that the cable rating is 67% that of the circuit breaker, not 50%, means that a ring has to be significantly out of balance to cause a problem. In a ring circuit, if any poor joint causes a high resistance on one branch of the ring, current will be unevenly distributed, possibly overloading the remaining conductor of the ring. See also Electrical wiring in the United Kingdom References External links Ring Circuit wiring guide Electrical wiring Electricity supply circuits