1930 Eicr

Alternating current is generally accepted to be more dangerous than direct current with regard to electric shock.

Direct current is more dangerous with regard to fire and arc flash.

Not sure about AC being more dangerouse than DC

It's the old War of the currents debate. Basically volt for volt it's much harder to push a heart into VF using d.c. than a.c. In the end a.c. won, not through safety considerations but practical reasons - you'd can't transmit electricity for long distances efficiently at low voltages and converting from high voltages to low voltages (in the old days) could only be done using a transformer - and transformers only work with a.c.

It's still recognised in the current regs - the lower limit for having to provide ADS is 50V for a.c. but 120V for d.c. (see table 41.1).

   - Andy.

But with AC it is easier to fight the no-let go. To be fair to them at the time that EICR was written the body of knowledge and research work we now have on shock current, mortality, and the interaction of AC frequency and  shock duration on the heart rate were all more than the 30 years into the future. The commercial driver, as noted was that AC can be transformed up and down for long distance low loss transmission, and the desire to get the generating plant out of town and to somewhere that coal could easily be delivered was becoming pretty much  irresistible. (as demand grew beyond the sort of thing you could put into the basement of a normal building.)

We know how short the last  leg of the 230V/400v mains distribution is  today and how uneconomic the cable size becomes when it has to be much longer than about a metre or two per volt of supply  (hands up if your transformer is  much more than 500yds from your property ? - no, not many of us is it...) But you would not expect to see generators at the density that we install transformers, it is very impractical, - except perhaps at a fair ground or pop festival, where it is very noticeable, and keeping them all fueled is a procedure in itself.

Mike.

Back in the good old days of DC mains, distribution was often at 11kv 3 phase AC with a stepdown transformer and a rotary converter to produce DC nearer the load. Mercury arc rectifiers were sometimes used, but rotary converters gave a smoother output and the voltage could be adjusted by manipulating the field current in the rotary.

The earlier rotary converter substations were manned, but later they were automated. 

Made me smile. 

https://fb.watch/cWw_AR10_b/

Could it be that those old steam engines are exempt from ULEZ?