How many power groups does an AV rack need?
Add up the real power draw of everything in the rack, then divide by what one group can safely carry. Plan for 80% of the breaker rating so equipment that runs all day, plus start-up surges, doesn't trip it.
| Group | Maximum | Plan up to (80%) |
|---|---|---|
| 230 V × 10 A | 2,300 W | 1,840 W |
| 230 V × 16 A | 3,680 W | 2,944 W |
| 120 V × 15 A | 1,800 W | 1,440 W |
| 120 V × 20 A | 2,400 W | 1,920 W |
Example: a rack drawing 2,500 W needs two 10 A groups or one 16 A group in Europe, or two 20 A circuits in the US.
Use real draw, not nameplate ratings
- Amplifiers: use the draw at 1/8 power from the datasheet for speech and background music, 1/3 power for loud events. Using the full rated output wildly oversizes the circuits.
- PoE switches: use the switch's own draw plus the PoE power your devices actually use, not the full PoE budget, unless you plan to fill it.
- Power supplies: the number on the PSU is its maximum, not what the device normally draws.
Heat and UPS
Nearly all the power a rack uses ends up as heat in the room: 1 W = 3.41 BTU/h. A 1,000 W rack adds about 3,400 BTU/h, which a small closed room can't get rid of without ventilation or cooling.
For a UPS on the network and control gear, choose one whose watt rating is at least 25% above the load you put on it, and check the runtime chart for the load, not the maximum.
Good practice
- Put amplifiers on their own group, separate from network and control equipment.
- Give critical rooms two feeds (A and B) for equipment with dual power supplies.
- This is a planning estimate. The electrical installation must be designed and done by a licensed electrician.
Common questions
How much can I put on a 10 A group?
At 230 V a 10 A group is 2,300 W, and you should plan for about 1,840 W (80%). A 16 A group gives about 2,940 W planned.
Why plan for only 80%?
AV equipment often runs all day, and amplifiers draw large surges at power-on. Leaving 20% headroom avoids nuisance trips. In the US, the electrical code requires it for continuous loads.
Is 220 V the same as 230 V?
Yes, in practice. Europe standardised on 230 V decades ago, but many people still say 220 V. The US uses 120 V (often called 110 V) and 208/240 V for larger loads.
How do I convert watts to BTU/h?
Multiply by 3.412. For example, 1,500 W × 3.412 ≈ 5,120 BTU/h.