ion. The concept of a Restricted (The corresponding phrase in IEC 950 'for functional reasons' Access Area is a similar attempt, reflecting the telecom practice of leaves the same uncertainty). Filtering techniques not involving an locating hardware in a special room and locking the door, opening earth connection are to be preferred. If a telecom 'functional earth' it again only to people who know what an electrical hazard looks is needed, for earth signalling for example, this should preferably be like. In such a room, some of the accessibility requirements are a permanent and reliable connection, even though other ways are relaxed, and for the purpose of containing a fire that might start in allowed by the standard. The simpler, the better, especially when the equipment, the room may be regarded as the fire enclosure offering the equipment for third party testing and approval. Finally, instead of the box itself. At the date of publication this concept lacks even if it is known that the line wires are earthed somewhere, they both maturity and the support of some experts. In particular the must not be used to obtain an earth connection for anything at the meaning of 'where access is controlled' is not precise. Until the subscriber's end. subject becomes more stable, designers should if possible avoid using the relaxations proposed for equipment in a restricted access 23.6.5 TNV superseding classical safety area. Subclause 4.3.1 clearly states how EN 41003 is complementary to, 23.6.8 Overlap of two ENs and separate from, the classical safety standards, as shown in Figure 23.5. However, many of those standards contain rules which would EN 41003 and the telecom parts of IEC 950 are similar and may preclude the use of TNV circuits as permitted in EN 41003, which eventually be identical, SO that two ENs, EN 41003 and EN 60950 is why 4.3.2 is stated to apply 'in place of any more restrictive will eventually have these similar or identical requirements. How- requirement in the relevant standard'. ever, there will be a c