Effect of Emissivity and Number of Busses on Ampacity - Data here show how higher emissivities improve ampacity. Multiple busses also affect ampacity in a nonlinear relationship. Ampacity may be raised by increasing heat dissipation through the use of convection cooling or surface treatments. Surface treatments which improve emissivity are available.
| Number of 1/4x4 in. Busses | Ampacity, Amp | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 30 °C Rise | 50 °C Rise | 65 °C Rise | ||||||||||
| Emissivity | Emissivity | Emissivity | ||||||||||
| 0.15 | 0.4 | 0.7 | 0.9 | 0.15 | 0.4 | 0.7 | 0.9 | 0.15 | 0.4 | 0.7 | 0.9 | |
| 1 | 1100 | 1250 | 1400 | 1600 | 1500 | 1700 | 1900 | 2000 | 1700 | 1950 | 2200 | 2300 |
| 2 | 1900 | 2050 | 2200 | 2300 | 2550 | 2750 | 2950 | 3100 | 2950 | 3200 | 3400 | 3600 |
| 3 | 2500 | 2700 | 2850 | 3000 | 3400 | 3600 | 3850 | 4000 | 3950 | 4200 | 4500 | 4600 |
| 4 | 3100 | 3300 | 3450 | 3600 | 4200 | 4400 | 4700 | 4800 | 4900 | 5100 | 5400 | 5600 |
| * 1/4 in. spacing. Ampacities of bus bar systems of other configurations must be calculated, taking into account size, spacing, number of bus bars and overall skin-effect ratio. | ||||||||||||