48V DC Telecoms Equipment Disconnection Time

Where is this listed in BS7671, is it 411.8 as this doesn't specify DC?

48V d.c. isn't RLV, but ELV. Disconnection times for ADS are per table 41.1 - which for ≤120V d.c. says no disconnection needed for protection against shock. (Basically ≤120V d.c.  is treated pretty much live ≤50V a.c. - i.e. in normal dry conditions is considered safe to touch).

You probably still need to protect conductors (or rather their insulation) from physical damage in the case of shorts and overloads - but the timing of that is much more open (5s is often used as a maximum for dead shorts, just to simplify the calculations, as things are mostly still adiabatic in that range).

   - Andy.

Where is this listed in BS7671, is it 411.8 as this doesn't specify DC?

48V d.c. isn't RLV, but ELV. Disconnection times for ADS are per table 41.1 - which for ≤120V d.c. says no disconnection needed for protection against shock. (Basically ≤120V d.c.  is treated pretty much live ≤50V a.c. - i.e. in normal dry conditions is considered safe to touch).

You probably still need to protect conductors (or rather their insulation) from physical damage in the case of shorts and overloads - but the timing of that is much more open (5s is often used as a maximum for dead shorts, just to simplify the calculations, as things are mostly still adiabatic in that range).

   - Andy.