UL 60950 3rd Edition (formerly UL 1950, 3rd edition)
Table 4.15 Minimum Clearances in Secondary Circuits (millimeters)
Nominal AC
Mains Supply
voltage
Working
Voltage up
to and
Nominal AC Mains Supply voltage
?ꢂ150 V
Nominal AC Mains Supply voltage
> 150 V ? 300 V
> 300 V ? 600 V
(transient rating
for Secondary
Circuit 2500 V)
Circuit Not
Subject to
(transient rating for Secondary
Circuit 800 V)
(transient rating for Secondary
Circuit 1500 V)
Transient
including
Overvoltages
Pollution
Pollution
Degrees 1 and 2
only
Pollution
Pollution
Degree 3
Pollution
Pollution
Degree 3
Degrees
Degrees 1 and 2
Degrees 1 and 2
1, 2, and 3
V * V **
F
0.4
B/S
0.7
0.7
0.9
R
F
1
1
1
B/S
1.3
1.3
1.3
R
F
B/S
1
1
R
2
2
2
F
1
1
1
B/S
1.3
1.3
1.3
R
F
B/S
2
2
2
2
R
4
4
4
4
4
F
B/S
0.4
0.7
0.7
1.1
1.4
R
71
50
1.4
1.4
1.8
2.6
2.6
2.6
0.7
0.7
0.7
2.6
2.6
2.6
1.7
1.7
1.7
1.7
1.7
0.4
0.6
0.6
1.1
1.4
0.8
1.4
1.4
2.2
2.8
140 100 0.6
210 150 0.6
280 200
1
F 1.1; B/S 1.4; R 2.8
F 1.6; B/S 1.94; R 3.8
420 300
2
* Voltage peak or DC
** Voltage rms (sinusoidal)
Note: F = Functional
B/S = Basic/Supplementary
R = Reinforced
Table 4.16 Minimum Creepage Distances (millimeters)
Functional, Basic, and Supplementary Insulation
Pollution Degree 2
Working
Voltage
Pollution Degree 1
Material Group
I, II, IIIa, or IIIb
Pollution Degree 3
Material Group
Material Group
V
RMS or DC
I
II
0.9
1
IIIa or IIIb
I
1.5
1.8
1.9
2
2.5
3.2
4
5
8
10
12.5
II
1.7
2
IIIa or IIIb
1.9
2.2
2.4
2.5
3.2
4
? 50
100
125
150
200
250
300
400
600
800
1000
Use the Clearance from the
0.6
0.7
0.8
0.8
1
1.3
1.6
2
1.2
1.4
1.5
1.6
2
2.5
3.2
4
appropriate table
1.1
1.1
1.4
1.8
2.2
2.8
4.5
5.6
7.1
2.1
2.2
2.8
3.6
4.5
5.6
9.6
11
5
6.3
10
12.5
16
3.2
4
5
6.3
8
10
14
Note: Linear interpolation is permitted between the nearest two points, the calculated spacing being rounded to the next higher 0.1 mm
increment.
The following separations require the specified insulation grade:
•
•
•
•
TNV3 from TNV3 — functional insulation
TNV3 from SELV — basic insulation
TNV3 from TNV1 — basic insulation
TNV3 from TNV2 — basic insulation
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SIDACtor Data Book and Design Guide
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