Quote
I meant a 133/230V wye system without the neutral brought into the house. These are older installations, where at the time used to be 110V.
Was it actually 110V, or were these systems at one time the nominal 127/220V systems as were used in some parts of France?

On the ring circuits, you'll find many smaller houses wired back in the 1950s or 1960s which do indeed have only a single 30A ring feeding all the receptacles. These days it's more usual to have two rings in the average house, or even three. Our rules state that each ring can serve a floor areas of up to 100 sq. meters.

Standard lampholders are allowed to be wired on any circuit up to a maximum of 16A, but in residential wiring 5 or 6A lighting circuits are the norm. Again, in many old properties with just a few lights one 5A lighting circuit was common, but two or more are the norm these days. We have separate circuits for electric range (cooker), water heaters, etc.

Many European countries seem to use 16A circuits feeding a mixture of receptacles and lights, but in France they seem to favor separate 10A lighting circuits.

Yes, in TN systems with no main RCD/GFI, then the fuses provide both overcurrent and ground-fault protection. There are still plenty of old (and not so old!) installations which use rewireable fuses. Why these remained so popular in the U.K. for so long, I don't know. Their characteristics are such that for many years the IEE current-rating tables specified ampacity based on these fuses with a footnote to the effect that ratings could be increased by 33% if cartridge fuses were used instead.

On the main ground lead, in the average residential system here we have 25 sq. mm phase and neutral on the service with a 16 sq. mm ground.

Re the American 4-wire delta, Sparky's provided the link I was about to search for in the Tech. Reference area. Thanks Steve!

Exploding appliances? Certainly reversed wiring at a recept. could result in some glowing cords given a fault and only a 30A OCPD! [Linked Image]