Installing Elevator Annunciators.
The installing of electric bells and annunciators in elevators does not present any special problems, although the apparatus used must be selected with a view to its being suitable to withstand the shocks incident to elevator service.
Fig. 60
In general the wires leading from the push buttons on the different floors to the bell or annunciator in the elevator, are flexible and made up into a cable. One end of this cable is attached to the underside of the elevator car, the other end being fixed usually to the elevator wall, at a point midway between the top and bottom of the shaft.
In [Fig. 61] is shown a diagram of the general circuit used, details of course differing in each installation.
One point to be taken care of in elevator work is the attachment of the cables. The continual movement tends to break the wires at the two ends if good flexible cable is not used and the installation done in a workmanlike manner.
Elevator cable is a standard article and may be procured through any electrical supply store. That most commonly used consists of the requisite number of copper conductors each composed of 16 strands No. 30 B. and S. gauge soft and untinned copper wire. These flexible conductors are insulated with two reverse wrappings of cotton and one braid of cotton. The insulated conductors are cabled together with a steel supporting strand where extra tensile strength is required, as in the case of extra long cables. The number of conductors generally ranges from 3 to 20 inclusive.
The wires leading from the push buttons to the cable should be preferably rubber covered and braided. Only where economy at the outset is desired may ordinary annunciator or office wires be employed.
Fig. 61
A connection block carrying binding posts is used at each point where the cable connects to the push button wires or to the annunciator. This may be home-made or purchased ready made, as desired.