State Industries SW 37-670 Electrical Data, Branch Circuit, Boiler Circuits, Control Circuit

ELECTRICAL DATA

General

Check the boiler model and rating plate information against the characteristics of the branch circuit electrical supply. Do not connect the boiler to an improper source of electricity.

Voltage applied to the boiler 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 boiler is filled with water. Doing so may cause the heating elements to burn out. Such damage is not covered under the terms of the warranty.

The branch circuit is connected to the block through an opening provided on top of the boiler.

The boiler should be connected to a separate, grounded, branch circuit with overcurrent protection and disconnect switch. These are part of the electrical supply system not components of the boiler, as such they are obtained locally. The boiler should be grounded in accordance with national and local codes.

Branch Circuit

The branch circuit wire size should be established through reference to the National Electrical Code or other locally approved source in conjunction with boiler amperage rating. Branch circuit wiring which connects to the boiler terminal block should be temperature rated at 75°C. For convenience, portions of the wire size tables from the Code are reproduced here. It is suggested the electrician size the branch circuit at 125 percent of the boiler rating and further increase wire size as necessary to compensate for voltage drop in long runs. Branch circuit voltage drop should not exceed 3% at the boiler.

Calculating Amperage/

Overcurrent Protection

The boiler is factory wired for connection to three wire single-phase or three and four wire three-phase branch circuits. In addition, a ground conductor may be required.

A diagram of the wiring “as built” is furnished with the boiler for the electrician’s use. An amperage table is on pages 7 & 12 of this manual. The boiler model and rating plate provides full load amperage data. Typical or Standard wiring diagrams are provided on pages 13 & 14 of this manual.

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.

Boiler Circuits

The boiler’s electrical components are pictured and identified on page 8. The model and rating plate illustration on page 9 identifies the electrical characteristics. Basically, there are two electrical circuits:

•The control circuit, where the temperature control directly or indirectly operates the contactor coils.

•The power circuit, which is operated by the control circuit, carries the electrical load of the heating elements.

The following describes the circuits and includes typical wiring diagrams. All circuits are designed for 60 or 50 Hertz alternating current.

Refer to ELECTRICAL CONFIGURATION TABLE, below, and wiring diagram provided with your boiler before completing connections to electrical supply.

NOTE: Wiring diagrams in this manual are typical examples. The specific wiring diagram “as built” for your boiler is typically attached to the “inner side” of the control panel.

Control Circuit

All control circuits are operated on single-phase 120V. A transformer is used in the control circuit.

Control circuit wiring is 14 Awg, THHN or THWN type, rated 600 volts, 105°C.

Seperate instructional literature is provided with the boiler for step control.

Portion of Table 310-16			Portion of Table 310-16
Allowable Ampacities of Insulated			Allowable Ampacities of Insulated
Copper Conductors			Aluminum and Copper-Clad
Not more than three conductors in			Aluminum Conductors
raceway or cable or direct burial			Not more than three conductors in
(based on ambient temperature of			raceway or cable or direct burial
	30°C, 86°F.)		(based on ambient temperature of
				30°C, 86°F.)
		Temperature			Temperature
		Rating of			Rating of
		Conductor. See			Conductor. See
		Table 310-13 in			Table 310-13 in
Size		Code	Size		Code
		75°C (167°F)			75°C (167°F)
AWG		Types RH,	AWG		Types RH,
		RHW, RUH (14-			RHW, RUH (12-
MCM			MCM
		2), THW, THWN,			2), THW, THWN,
		XHHW, USE			XHHW, USE
18		- - - - -	12		15
16		- - - - -	10		25
14		15	8		40
12		20	6		50
10		30	4		65
8		45	3		75
6		65	2		90
4		85	1		100
3		100	1/0		120
2		115	2/0		135
1		130	3/0		155
1/0		150	4/0		180
2/0		175	250		205
3/0		200	300		230
4/0		230	350		250
250		255	400		270
300		285	500		310
350		310	600		340
400		335	700		375
500		380	750		385
600		420	800		395
700		460	900		425
750		475	1000		445
800		490	1250		485
900		520	1500		520
1000		545	1750		545
			2000		560
1250		590
1500		625	These capacites relate		only to conductors
1750		650	described in Table 310-13 in Code.
2000		665	For ambient temperatures over 30°C, see
			Correction Factors, Note 13 in Code

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