Furnace

An electrically heated furnace, the furnace comprising:

• a. A furnace cabin, the furnace cabin comprising:
• i. one or more process tubes which extend through the furnace cabin and
• ii. a plurality of electrically powered heating means located inside the furnace cabin for heating the one or more process tubes,
• b. Electricity supply means located outside the furnace cabin for providing electricity to the electrically powered heating means, wherein
• a. the electricity supply means comprises one or more hermetically sealed boxes, connected externally to the furnace cabin, but spaced away from the furnace cabin, and
• b. the plurality of electrically powered heating means are connected to an electricity supply within the one or more hermetically sealed boxes by one or more electrical connecting rods which pass through a wall of the one or more hermetically sealed boxes, the one or more electrical connecting rods passing through the wall of the one or more hermetically sealed boxes through one or more hermetically sealed electrical feed-throughs.