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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. A design of the switchboard shall be submitted with the bid.
(Note.—This specification includes only the instruments used in the simplest of installations. The instruments required for any particular installation must, of course, 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 for connecting system with
dynamos in the building or with external source of supply.
double-pole fusible cut-outs.
(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.
'io. connec- All connecting wires shall be carried back
tions (c,iin- .,11. i .,i
ceaied). of the switchboard using only insulated
wire. All joints shall be soldered. AH 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.
3i. connoc- All dynamo, 'bus, feeder and riser wires
turns <sur- J
1'ICU), shall be of j P^lated J 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 j gU^face [ of the board using
insulated 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 W. Circuit*, switchboard:
(Enumeration of circuits
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:
S3.0yiiamo(s). dynamo(s) (each) having a capacity
of , c. p., incandescent lamps. The
maximum voltage at the terminals of the
dynamo(s) shall not exceed volts at full
The dynamo(s) shall he 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; the dynamo(s) shall be of such design that the power required will be automatically proportioned to the number and candle-power of the lamps burning at any time; if of the
shall be so designed that with the proper connections two or more may be operated successfully iu series, so that with ordinary care and precaution any dynamo may be added to or taken from the circuitnvithout 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, constantpotential type | j^1^ I 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 remaining dynamos in circuit or causing any change in the candle