Quote
How common is the fused grounded conductor shown in the first picture?

In earliest times, grounded conductors were always fused wherever ungrounded conductors were fused. By 1922 (the oldest NEC in my possession), it was realized that this could cause major headaches in multiwire circuits, thus this practice was no longer required nor permitted. However, authorities were divided for many years thereafter over whether it was safer to fuse or not to fuse the grounded conductor of a two-wire circuit.

I have catalogs from the '30s that offer equipment in a choice of fused or solid neutral, depending on what your local inspector wanted. One 1936 catalog offers a "GROUNDED CIRCUIT PLUG-- Designed for permanently grounding neutral". It was to screw into an Edison-base fuseholder. (The professional alternative to pennies!) [Linked Image]

The company where I apprenticed had two old porcelain 3-pole 30A fuse blocks on display in the shop. Each had a piece of 1/2" all-thread soldered into the neutral fuseholder.

I think in some areas, neutrals were fused into the '40s. I've never seen this in work from the '50s.

[This message has been edited by yaktx (edited 02-03-2006).]