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31. Connections (surface).

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 im-
possible 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. W. G. shall be used.

B. & S. or

All dynamo, bus, feeder and riser wires
wire fastened

shall be of insulated
bare

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

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section. All minor con

nections, such as to pressure indicators, ground detectors, etc., shall be made on

the

{

rear

surface

of the board using

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

G. shall be used.

B. & S. or

B. W.

The following circuits will centre at the 32. Circuits. switchboard:

(Enumeration of circuits

To different floors;

To different sections of the building;

Residence circuits;

Commercial circuits;

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

danger 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 shall be so designed that

type

they

it

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{they 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

{

they

it

will not be

injured if subjected to an overload of

per cent. above such rating for a period

of

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