I would support the use of higher voltages in large premises, 400/690 certainly and perhaps even 690/1k2

In most large premises, lighting and/or electric motors are often a large part of the load, and lighting ballasts are available for 400 volts. All but the smallest electric motors tend to have 400 volt windings suitable for delta connection on 230/400 volt systems  or for star connection on 400/690 volts.

The drawback is the need to still supply 230 volts single phase for loads that need it.

690/1,200 is more problematic as equipment choice is more limited, and of course 1,200 volts is considered high voltage

broadgage said:

and lighting ballasts are available for 400 volts.

Mercury (including fluorescent) lamps now banned, although other discharge lamps such as SON/SOX etc. will be available until at least 2027. However, as evidenced from street lighting, discharge lamps are being phased out for more energy efficient alternatives.

Other technologies ... chiefly LED ... are taking over now.

LED is not always low power if you have enough of them. This driver for example can put up to 400V across a string of LEDs taking a touch over a couple of amps per string
Pricey, but you only need one per lighting tower to turn night into day.
(and so the generator at the bottom runs for days.)
Eye damage at close range really is a consideration, the lights should only be on full power once  the pole is up.

the lumens per watt are about twice as good as the SON type if driving this sort of thing


Mike

It is not only DNOs  A friend has just been forced by the mortgage provider for his newly purchased private home to merge two previous Supplies into one as a condition of agreeing to provide the mortgage. 

mapj1 said:

LED is not always low power if you have enough of them.

mapj1 said:

the lumens per watt are about twice as good as the SON type if driving this sort of thing

Agreed ... isn't stopping the charge to LED though.

I was chiefly trying to point out that, for good or bad, the '400 V ballast' isn't really the way things are heading.

Except that the LED driver I linked to has a 180- 585 volt input range, to allow use as a 400v fitting, and also  leaving me wondering if the design  aimed for 600V and missed;-)

M

Any idea what the perceived risk is?

I can think of 50 good reasons for mimimizing the number of supplies.

Regulation 411.3.1.1 (2nd para) being one.

As I wrote earlier, I am only 99% certain that my two supplies have a common earth. They are only 10 m apart in the same street, but I cannot be certain.

The transformer in my street has recently been replaced, and it appears to indicate where the next transformers are in the same mains, so there really can be only one cable in the street.

Isn't the risk (of two earths) electrocution rather than burning the house down?

My 50 reasons are the 50 p/day standing charge, much higher than it was originally.

Chris Pearson said:

Isn't the risk (of two earths) electrocution rather than burning the house down?

Both. And they are both accounted for in BS 7671:

• Electrocution if the two earths are not bonded together to form "the same earthing system" (Regulation 411.3.1.1)
  
  
• Fire if diverted LV or HV fault current travels between the two because any protective conductors (or adjoining metalwork) can't carry sufficient current (Regulation 542.1.3.3).