@Dr Bunsen 561198 wrote:

I read recently it’s illegal in this country to wire your house up to a network other than casually stringing a network cable accross the house unless you’re a qualified electrician.

Is it the same im the UK?

no, computer networks, telecom cable, burglar alarms and other signalling cable are normally classed as extra low voltage and can still be done as DIY jobs. There are some new rules which are a bit silly as they mean I am classed as a competent person for 230V and 400V industrial electricity work as well as telecoms/computers, but at home there are bits of mains wiring I am not allowed to work on :rant: which I could right up until 2005.

Not sure about other EU nations (Scandinavia may be stricter) but there is a safety rule that all telecoms/signal cable must be at least 150mm from other cables carrying strong voltage or other power cable (as even a 12V or 48V DC supply can short circuit and set a fire if there are not enough fuses), and that telecoms functional earth (rarely used nowadays) and protective earth (or signal ground and earth ground) must be bonded at some point (which is good for safety but not always for signal quality!)

With telecom cable you have to be a bit more careful as there is 100V or more when a phone rings, ISDN can have 120V on the pairs (this does bite), some other PABX systems use 120V on the pairs to strike a neon lamp on a standard telephone set as a message waiting warning (as this lamp can also be used to indicate ringing).

If its going outside to the PTT line there is a chance that a fault could have made a pair contact strong voltage (especially in rural areas where utility poles are shared between telecoms and power company). However this normally blows the fuse at the telephone exchange and the folk who have to work up poles and in access trenches half full with water tend to look out for this sort of thing.

A hit from telecom volts is rarely harmful from the electricity itself, but because distribution boxes are often at height or in inaccessible places, the reflex that causes you to move back can put you off the ladder/or out of the roofspace and result in other injuries…