Fixing motor for Myford Ml7

The round-pin style came in 4 different sizes: 2A, 5A, 15A and 30A.

Before square pin plugs and sockets, UK domestic wiring was wired on a spur system where each socket connected back to a separate fuse. Spurs could be of different current capacities and to stop people burning the house down different sized plugs were used to make sure a 2A device couldn't be plugged into a 30A spur, or a 30A device into a 15A spur. No need for round-pin plugs to contain a fuse because there was one in the fuse box.

The spur system was fine when people only needed a few sockets, but it's inconvenient in a modern home.

In 1947 the system changed to wire houses with ring mains rather than spurs. A ring main can have many sockets connected to it, which suits modern needs. Although the main is protected by a single big fuse, each appliance needs to have a fused plug. All square-pin plugs are the same physical size, but they can be fitted with different fuses as necessary to suit the appliance. I have 1A, 2A, 3A, 5A, 7A and 13A examples, but 3 and 13A are the most common.

A 13A plug and fuse would be OK for a Myford.

Maybe the lathe should never have been fitted with a 5A plug, but not all lathe owners were electricians! Sparey's "The Amateur's Lathe' is well worth reading. Excellent book apart from things like carbide inserts that came later, but his comments on 1950's home workshop electrics make it clear that quite a few chaps back then lived dangerously! It's not a problem though : the wiring and switches etc could all be replaced if necessary.

Dave

It puzzles me that the original plug says 5A on it, can anyone offer an explanation?

In the olden days they were two sizes of plug the one shown in your pic rated at 5A then there was a larger version of that type of round plug rated at 15A, then with the coming of the ring main 13A became the standard .

Have not read all post's but have you tried disconnecting the motor to see if the fuse blows ?

H