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not only should questions of convenience be considered, but also questions of its relation to economy in the wiring.
The switchboard shall be made of ,
neatly and substantially built, of sufficient size to accommodate all the regulating apparatus, switches, bus bars, etc., named below without crowding, supported
on a stout framing of' , and set out not
less than from the wall.
(Note.—This specification includes only the instruments used in the simplest of installations. The instruments required for any particular installation must be determined by its individual purposes and necessities.)
There shall be placed upon this switchboard all the dynamo regulating apparatus and the following appliances:
main ampere meters.
-ampere meters for risers.
dynamo galvanometer switches.
(switches, cut-outs, etc., for purely local conditions).
All switches carrying over amperes
shall be knife switches; all other switches shall have sliding contacts, and shall make and break contact automatically beyond the control of the operator, who shall simply set the switch at the point of making or breaking.
Cut-outs shall be so protected that the molten metal cannot be spattered about on the fusing of the strip.
All switches and cut-outs shall be mounted on incombustible bases.
All connecting wires shall be carried
30. Connections (oon
back of the switchboard using only oealti^
wire. All joints shall be soldered.
All connections to switches, cut-outs, etc., shall be soldered or made with an approved form of lug or set screw, in all cases care being taken to secure good and sufficient contact to prevent heating and insure permanency; when made with lugs or set screws they shall be in plain sight and easily accessible for tightening. Connecting wires shall be so run and secured that crosses or grounds are impossible in the normal operation of the plant. All main wires shall have a
capacity of at least C. M. per ampere
and no wire smaller than B. & S. or
B. W. G. shall be used.
tSSKSSi). All dynamo, bus, feeder and riser wires
shall be of | -Sated [wire fastened
neatly and securely to the front surface of the switchboard. All bare wires shall be separated from the board by an air
space of not less than . Bus bars
shall be of section. All minor connections, such as to pressure indicators, ground detectors, etc., shall be made on
the]Sace[of the board "dug — wire. All joints shall be soldered. All connections to switches, cut-outs, etc., shall be soldered or made with an approved form of lug or set screw, in all cases care being taken to secure good and sufficient contact to prevent heating and insure permanency; when made with lugs or set screws they shall be in plain sight and easily accessible for tightening. All main wires shall have a capacity of at
least C. M. per ampere, and no wire
smaller than B. & S. or B. W.
Gr. shall be used.
The following circuits will centre at the 32. circuits, switchboard: (Enumeration of circuits
To different floors;
To different sections of the building;
Street lighting circuits;
Power circuits, etc. This enumeration will largely determine the extra instruments to be supplied.)
Incandescent Series System, Dynamos Medium or High Potential (Variable or Constant), Current Direct or Alternating.
This contractor shall furnish, and, unless otherwise specified, erect the following apparatus and material:
33. Dynamos. (See Note: p. 43, sec. 21.)
dynamo(s) (each) having a capacity of kilowatts. The maximum
voltage at the terminals of the dynamo(s) shall not exceed volts at full load.
The dynamo (s) shall be of the latest and most efficient pattern; mounted on a base provided with an adjustable belt tightener so that the belt may be tightened while in operation; capable of operating
under full load for consecutive hours
without increasing the temperature of any part, especially the armature, fields and commutator, to such a degree as to en