11
ELECTRICAL
GENERAL
The installation must conform with these instructions and the local
code authority having jurisdiction and the requirements of the power
company. In the absence of local codes, the installation must comply
with the current editions of the National Electrical Code, NFPA 70 or
the Canadian Electrical Code CSA C22.1.
An electrical ground is required to reduce risk of electrical shock
or possible electrocution. The water heater should be connected
to a separate grounded branch circuit with over-current protection
and disconnect switch. The water heater should be grounded in
accordance with national and local codes.
Voltage applied to the heater should not vary more than +5% to -10%
of the model and rating plate marking for satisfactory operation.
DO NOT ENERGIZE THE BRANCH CIRCUIT FOR ANY REASON
BEFORE THE WATER HEATER TANK IS FILLED WITH WATER.
DOING SO WILL CAUSE THE HEATING ELEMENTS TO BURN
OUT AND VOID WARRANTY.
The factory wiring should be connected to the branch circuit wiring
within the provided junction box. The water heater should be
connected to a separate, grounded, branch circuit with overcurrent
protection and disconnect switch. The water heater should be
grounded in accordance with national and local codes.
BRANCH CIRCUIT
The branch circuit wire size should be established through reference
to the current edition of NFPA-70, the National Electrical Code
or other locally approved source in conjunction with the heater
amperage rating. For convenience, portions of the wire size tables
from the Code are reproduced here. The branch circuit should be
sized at 125 percent of the heater rating and further increase wire
size as necessary to compensate for voltage drop in long runs.
CALCULATING AMPERAGE/OVERCURRENT PROTECTION
The water heaters come from the factory in two configurations:
1. Two wire T-6 circuit for dual element water heater equipped with
a single high limit control and single phase power input.
2. Four wire T-4 circuit for dual element water heater equipped with
two high limit controls and single phase power input.
This is an example of calculating heater amperage for both types
of element operation. From this, the branch circuit conductor and
overcurrent protection sizing can be established.
The example (T-4) is of a single-phase 240 volt unit with two, 3 kw
elements. Check the water heater model and rating plate for actual
specifications and substitute those values in the following.
TABLE 3
Non-simultaneous:
(T6 - Circuit)
Simultaneous:
(T4 - Circuit)
3000 ÷ 240 = 12.5 amps*
6000 ÷ 240 = 25 amps*
*NOTE: as a single-phase non-
simultaneous unit.
*NOTE: as a single-phase
simultaneous unit.
The rating of the overcurrent protection should be computed on the
basis of 125 percent of the total connected load amperage. Where the
standard ratings and settings do not correspond with this computation,
the next higher standard rating or setting should be selected.
Portion of Table 310-16 (NFPA-70) follows:
Allowable Ampacities of Insulated Copper Conductors. Not more
than three conductors in Raceway or Cable or Direct Burial (Based
on Ambient Temperature of 30° C, 86° F).
These ampacities relate only to conductors described in Table
310-16 in Code.
For ambient temperatures over 30° C (86° F), see Correction
Factors, Note 13 in Code.
TABLE 4
Size
Temperature Rating of Conductor
See Table 310-16 in Code
AMG
MCM
60°C
(140°F)
75°C
(167°F)
Types:
RUW, (14-2), T, TW, UF
Types:
RH, RHW, RUH, (14-2),
THW, THWN, XHHW, USE
18
16
14
- - -
- - -
15
- - -
- - -
15
12
10
8
20
30
40
20
30
45
6
4
3
55
70
80
65
85
100
Portion of Table 310-18 follows:
Allowable Ampacities of Insulated Aluminum and Copper -Clad
Aluminum Conductors.
Not more than three conductors in Raceway or Cable or Direct Burial
(Based on Ambient Temperature of 30° C, 86° F. These ampacities
relate only to conductors described in Table 310-18 in Code.
For ambient temperatures over 30° C (86° F), see Correction Factors,
Note 13 in Code.
TABLE 5
Size
Temperature Rating of Conductor
See Table 310-18 in Code
AMG
MCM
60°C
(140°F)
75°C
(167°F)
Types:
RUW, (12-2), T, TW, UF
Types:
RH, RHW, RUH, (12-2),
THW, THWN, XHHW, USE
12
10
15
25
15
25
8
6
30
40
40
50
4
3
55
65
65
75
2
1
75
85
90
100
