Schneider Electric 9070 manual Primary Fusing to Meet NEC, Volts

Industrial Control Transformers

Fuse Protection

Primary Fusing to Meet NEC

Recommended Fuse Sizes for the PRIMARY (use class CC time delay fuses) to Meet NEC

		120 Volts			240 Volts			480 Volts			600 Volts
VA		Fuse	Fuse		Fuse	Fuse		Fuse	Fuse		Fuse	Fuse
	Primary		Rating	Primary		Rating	Primary		Rating	Primary		Rating
		Rating with			Rating with			Rating with			Rating with
	Current	Secondary	without	Current	Secondary	without	Current	Secondary	without	Current	Secondary	without
	Amperes		Secondary	Amperes		Secondary	Amperes		Secondary	Amperes		Secondary
		Protection			Protection			Protection			Protection
			Protection			Protection			Protection			Protection
25	0.21	1/2	1/2	0.10	1/4	1/4	0.05	1/8	1/8	0.04	1/10	1/10
50	0.41	1	1	0.21	1/2	1/2	0.10	2/10	2/10	0.08	2/10	2/10
75	0.63	1-1/2	1-1/2	0.31	6/10	6/10	0.16	3/10	3/10	0.13	3/10	3/10
100	0.83	2	2	0.42	1	1	0.21	1/2	1/2	0.17	4/10	4/10
150	1.25	3	3	0.63	1-1/2	1-1/2	0.31	6/10	6/10	0.25	6/10	6/10
200	1.67	4	4	0.83	2	2	0.42	1	1	0.33	8/10	8/10
250	2.08	5	3-2/10	1.04	2-1/2	2-1/2	0.52	1-1/2	1-1/4	0.42	1	1
300	2.50	6-1/4	4	1.25	3	3	0.63	2	1-1/2	0.50	1-1/8	1-1/8
350	2.92	7	4-1/2	1.46	3-1/2	3-1/2	0.73	2-1/2	1-8/10	0.58	1-4/10	1-4/10
500	4.17	10	6-1/4	2.08	5	3-2/10	1.04	3	2-1/2	0.83	2	2
750	6.25	15	10	3.13	7-1/2	5	1.56	3-1/2	3-1/2	1.25	3	3
1000	8.33	20	12	4.17	10	6-1/4	2.08	5	3-2/10	1.67	4	4
1500	12.50	N/A	15	6.25	15	10	3.13	7-1/2	5	2.50	6-1/4	4
2000	16.66	N/A	20	8.33	20	12	4.17	10	6 1/4	3.33	8	5

NOTES:

•Recommended fuse sizes per NEC Article 450-3.

•Transformers with primary only, select protection at 125%, if a standard size rating is not available, go to next higher rating.

•Transformers with primary only and current rating is less than 9 A, select protection at no more than 167%.

•Transformers with primary only and current rating is less than 2 A, select protection at no more than 300%.

•Transformers with primary and secondary, select primary protection at not more than 250% and secondary at 125%. If a standard size rating is not available, go to next higher standard rating.

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