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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.
aons^aPtTceh All dynamo, bus, feeder and riser wires shall be of | Seated}TM 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 | surface f of the board usinS
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.
G. 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 endanger the insulation or decrease the efficiency of operation; shall not spark unduly with proper care of the commutator and adjustment of the brushes, nor under considerable variation of load; shall have an insulation resistance of not less than
ohms between all parts insulated
from each other; shall be adapted to operate at such speed as will allow the use of high-speed, automatic cut-off engines belted direct; shall be provided with efficient oiling devices; the armature shall be balanced both electrically and mechanically so that there will be no tendency to spring the shaft or to draw the armature toward either bearing so as to cause excessive friction and heating, and no vibration; if of the direct and constant-current
type | |^ey | shall be so designed that
with the proper connections two or more may be operated successfully in series, so that with ordinary care and precaution any dynamo may be added to or taken from the circuit without in any manner affecting the efficient operation of the remainder, and with but a momentary fluctuation in the candle-power and steadiness of the lamps; if of the direct-current,
constant-potential type j |^ey | shall be
so designed that with the proper connections two or more may be operated successfully in parallel so that with ordinary care and precaution any dynamo may be added to or taken from the circuit without in any manner affecting the operation of the dynamos remaining in circuit or causing any change in the candle-power of the lamps; and that when two or more are operating on the same circuit the load may be divided between them in proportion to their respective capacities under all conditions from no load to full load. The dynamo(s) shall be rated with such
margin of safety that j I will not be
injured if subjected to an overload of
per cent, above such rating for a period of .