Table 3 — Maximum Gas Flow Capacity*
NOMINAL
IRON PIPE,
SIZE
(in.)
INTERNAL
DIAMETER
(in.)
LENGTH OF PIPE, FT†
10 20 30 40 50 60 70 80 90 100 125 150 175 200
1
⁄
2
.622 175 120 97 82 73 66 61 57 53 50 44 40 — —
3
⁄
4
.824 360 250 200 170 151 138 125 118 110 103 93 84 77 72
1 1.049 680 465 375 320 285 260 240 220 205 195 175 160 145 135
1
1
⁄
4
1.380 1400 950 770 600 580 530 490 460 430 400 360 325 300 280
1
1
⁄
2
1.610 2100 1460 1180 990 900 810 750 690 650 620 550 500 460 430
*Capacity of pipe in cu ft of gas per hr for gas pressure of 0.5 psig or less. Pressure drop of 0.5-in. wg (based on
a 0.60 specific gravity gas). Refer to Table C-4, National Fire Protection Association NFPA 54.
†This length includes an ordinary number of fittings.
X. STEP 10 — INSTALL ELECTRICAL CONNECTIONS
WARNING:
The unit cabinet must have an uninter-
rupted, unbroken electrical ground to minimize the pos-
sibility of personal injury if an electrical fault should
occur. This ground may consist of an electrical wire con-
nected to the unit ground lug in the control compart-
ment, or conduit approved for electrical ground when
installed in accordance with NEC (National Electrical
Code) ANSI/NFPA (latest edition) (in Canada, Cana-
dian Electrical Code CSA [Canadian Standards Asso-
ciation] C22.1) and local electrical codes. Do not use gas
piping as an electrical ground. Failure to adhere to this
warning could result in personal injury or death.
CAUTION:
Failure to follow these precautions could
result in damage to the unit being installed:
1. Make all electrical connections in accordance with NEC
ANSI/NFPA(latest edition) and local electrical codes gov-
erning such wiring. In Canada, all electrical connec-
tions must be in accordance with CSA standard C22.1
Canadian Electrical Code Part 1 and applicable local codes.
Refer to unit wiring diagram.
2. Use only copper conductor for connections between field-
supplied electrical disconnect switch and unit. DO NOT
USE ALUMINUM WIRE.
3. Be sure that high-voltage power to unit is within oper-
ating voltage range indicated on unit rating plate.
4. Do not damage internal components when drilling through
any panel to mount electrical hardware, conduit, etc. On
3-phase units, ensure phases are balanced within 2%.
Consult local power company for correction of improper
voltage and/or phase imbalance.
A. High-Voltage Connections
The unit must have a separate electrical service with a field-
supplied, waterproof, disconnect switch mounted at, or within
sight from, the unit. Refer to the unit rating plate for maxi-
mum fuse/circuit breaker size and minimum circuit amps (am-
pacity) for wire sizing. See Tables 4 and 5 for electrical data.
The field-supplied disconnect switch box may be mounted on
the unit over the high-voltage inlet hole when the standard
power and low-voltage entry points are used. See Fig. 2 and
3 for acceptable location.
See unit wiring label and Fig. 11 for reference when making
high voltage connections. Proceed as follows to complete the
high-voltage connections to the unit.
Fig. 9 — Supply and Return Duct Openings
Fig. 10 — Vertical Duct Cover Removed
—11—
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