Total connected load on a series AGL circuit — fixtures, isolating transformer losses and primary cable I²R loss, with an approximate CCR output voltage and loading check.
A series circuit is driven by a constant current regulator (CCR), so the CCR sees the sum of every fixture's power, the isolating transformer losses that come with it, and the loss in the primary cable itself. This tool adds those three parts, reports kW and kVA, and compares the result with a standard CCR size.
Enter the power each fixture draws at full brightness (rated series current), per fixture type on this circuit. Use the manufacturer's data sheet value.
| Fixture type / description | Quantity | Watts each (W) | Subtotal (W) | Remove |
|---|
Full-brightness series current. 6.6 A is the highest-step output of a standard 6.6 A (FAA Class 1) CCR. Class 2 circuits run at 20 A.
Planning assumption applied to all fixtures — replace with manufacturer data. Lightly loaded transformers (e.g. low-wattage LED) are less efficient.
Nominal DC resistance at 20 °C (IEC 60228 for mm² sizes). Verify against your cable data sheet.
Length is the full series loop out and back, i.e. the total primary cable in the circuit. Leave 0 to ignore cable loss.
Maximum loading is your project's own design rule, not a standard value. FAA AC 150/5345-10H lists CCR sizes of 1, 2, 4, 7.5, 10, 15, 20, 25, 30, 50 and 70 kW (rated in kW out; 50 and 70 kW are replacement-only). 2.5 and 5 are IEC and manufacturer sizes rated in kVA. The tool compares the circuit kVA with the nominal figure, which is the conservative reading.
| Fixture type | Qty | W each | Subtotal (W) | Share of fixture load |
|---|
Calculated load at full brightness — not a final design load. Verify against manufacturer data for the equipment selected.
Every step is shown so the result can be checked by hand.
Sum of quantity times rated watts for each fixture type at full brightness.
Each fixture is fed through an isolating transformer. Dividing by efficiency gives the power the primary circuit must supply.
The default 90 % is an editable planning value. Use the transformer data sheet at the actual load, because efficiency falls when a transformer is lightly loaded.
The cable carries the full series current, so its loss is I² times total loop resistance, corrected for temperature.
The voltage is an approximation for quick checking. It ignores secondary cable and connector losses and assumes the power factor entered.
| Item | Value |
|---|---|
| 100 fixtures × 45 W | 4,500 W |
| Transformer efficiency | 90 % |
| Load after transformers | 5,000 W |
| Cable | #8 AWG, 4,000 m, 20 °C |
| Cable resistance | 8.244 Ω |
| Cable loss at 6.6 A | 359 W |
| Total real power | 5,359 W (5.36 kW) |
| kVA at PF 0.95 | 5.64 kVA |
| Approx. output voltage | 855 V |
Loaded on a 7.5 kVA CCR: 75 % of the rating.
It does not size cable for voltage or insulation limits, model brightness steps, or account for secondary cable, connectors or lamp-out conditions. Dedicated CCR capacity, circuit voltage and cable tools are on the toolkit roadmap.
Quick answers on total connected load on a series AGL circuit and the CCR check.
It adds up the total connected load on a series AGL circuit, which is the fixtures, the isolating transformer losses and the primary cable I squared R loss. It reports kW and kVA, gives an approximate CCR output voltage, and compares the result with a standard CCR size.
The fixture load is the sum of quantity times rated watts at full brightness. The transformer losses come from dividing the fixture load by the transformer efficiency, and the default of 90 percent is an editable planning value. The cable loss is the current squared times the loop resistance, corrected for temperature. The total real power is the transformer-side load plus the cable loss.
The apparent power is the total real power divided by the load power factor, and the approximate output voltage is that kVA divided by the circuit current. The voltage is an approximation for quick checking. It ignores secondary cable and connector losses and assumes the power factor entered.
The tool compares the circuit kVA with the CCR nameplate rating, which is the conservative reading, and finds the smallest CCR that fits at your maximum loading. The maximum loading is your project's own design rule, not a standard value. FAA AC 150/5345-10H lists CCR sizes of 1, 2, 4, 7.5, 10, 15, 20, 25, 30, 50 and 70 kW, where 50 and 70 kW are replacement-only. The 2.5 and 5 sizes are IEC and manufacturer sizes rated in kVA.
Enter the full-brightness series current, which is 6.6 A for a standard FAA Class 1 CCR and 20 A for Class 2 circuits. The cable length is the full series loop, out and back, which is the total primary cable in the circuit. Leave it at 0 to ignore cable loss.
100 fixtures of 45 W give 4,500 W, and at 90 percent transformer efficiency the load is 5,000 W. Over 4,000 m of #8 AWG at 20 degrees C the cable resistance is 8.244 ohms and the loss at 6.6 A is 359 W. The total is 5,359 W, which is 5.64 kVA at a power factor of 0.95, with an approximate output voltage of 855 V. On a 7.5 kVA CCR the loading is 75 percent.
It does not size cable for voltage or insulation limits, model brightness steps, or account for secondary cable, connectors or lamp-out conditions.
No. It is a calculated load at full brightness and not a final design load. Lightly loaded transformers, such as those on low-wattage LED fixtures, are less efficient than the default. Final design shall be verified against manufacturer data for the fixtures, isolating transformers, cable and CCR selected for the project.
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