Old Electrical Equipment - MEM fusebox

Old MEM fusebox containing 3 ceramic rewireable fuses.

Closed view

Old MEM fusebox This box is mounted on a wooden board, which was the typical installation method for older fuseboxes and switchgear.

The cover is secured by the two screws. Note the switch recess is designed so that the cover can only be removed when the switch is in the OFF position - when in the ON position as shown, the switch itself prevents the cover from being removed.

The cover is made from a black plastic material. The area on the front which appears damaged is actually glue from a label which someone had unhelpfully placed on there, covering the two screws.

Inside the fusebox

Interior view of an old ceramic MEM fusebox This is the view after removing the front cover. The three ceramic fuses to the left are all 15A rewireable types. The two large screws in the recessed holes are what secures the fusebox to the wooden backboard.

The black area surrounding the switch is a plastic sheet to cover the live terminals underneath. Also note the metal tab to the left of the switch, which locks the switch in the OFF position. WHen the cover is replaced, this tab is depressed and unlocks the switch.

The supply wires can be seen below the switch, passing through two holes in the wooden backboard.

Fuse and shield removed

Interior view of a MEM ceramic fusebox One fuse has been removed, and the contacts can be seen. The lower contact is the supply, with the outgoing circuit connected to the upper terminal. This lower contact would be live when the main switch is on, hence the mechanical lock and cover design to ensure the switch is always OFF when the cover is removed.

The terminal shield has also been removed. The supply connects to the two terminals below the switch, and these would be live even with the switch off. The outgoing neutrals connect to the top right terminal, and the remains of three wires are still connected. These passed through a hole in the wooden backboard.

All fuses removed

Interior view of a MEM ceramic fusebox All of the fuses have been removed, and the mechanical lock overridden so that the switch can be put into the ON position.

The whole frame is a cast ceramic material, the wording such as '15A FUSES' and 'AC ONLY' being cast into the ceramic.

The switch is only rated to 30A, despite there being 3x15A fuses - it is likely however that the outgoing circuits would not be all loaded to the full capacity at the same time.