The Wire.

The size of the copper wire used in bell work is No. 16, or No. 18, B and S gauge, and sometimes smaller, such as No. 20 to 22. But smaller wire than No. 18 has too much resistance, and would necessitate a larger battery power, even if its mechanical strength were not too low. The insulating coverings are cotton saturated with paraffin wax or compounds.

The covered wires are variously known as annunciator, office, or weatherproof wire, these terms being mostly for distinction of the coverings and not for the use to which the wire would be put.

Annunciator wire has two layers of cotton merely wrapped around the copper and then saturated with paraffin.

Office wire has the two cotton layers braided, the inside one being filled with a moisture-repelling compound.

Both office and annunciator wires have their outside coverings filled with paraffin and highly polished.

From the ease with which annunciator wire is stripped of its cotton covering, the braided office wire is to be preferred. These coverings are made in a variety of colors.

Weatherproof covered wire is mostly used for electric light work, but the sizes given above are good for bell work, although their larger outside diameter makes them harder to conceal.

The approximate number of feet to the pound of office and annunciator wire is given in the table.

Office Wire.Annunciator Wire.
No.Feet per lb.No.Feet per lb.
12 3518180
14 5520225
16 95
18135