Low Voltage Landscape Lighting, Metric

Voltage Loss Per Meter Of Cable (One Way Distance, Both Conductors)

Watts @12V	WIRE GAUGE AWG and (mm²)
	18 (.82)	16 (1.31)	12 (3.31)	10 (5.26)	8 (8.37)
	WIRE RESISTANCE (Ohms/meter of cable, both conductors) @ 68 °F (21 °C)
	0.0438	0.0263	0.0102	0.0064	0.0041
1	0.0037	0.0022	0.0009	0.0005	0.0003
2	0.0073	0.0044	0.0017	0.0011	0.0007
3	0.0110	0.0066	0.0026	0.0016	0.0010
4	0.0146	0.0088	0.0034	0.0021	0.0014
5	0.0183	0.0110	0.0043	0.0027	0.0017
6	0.0219	0.0132	0.0051	0.0032	0.0021
7	0.0256	0.0153	0.0060	0.0037	0.0024
8	0.0292	0.0175	0.0068	0.0043	0.0027
9	0.0329	0.0197	0.0077	0.0048	0.0031
10	0.0365	0.0219	0.0085	0.0053	0.0034
20	0.0730	0.0438	0.0170	0.0107	0.0068
30	0.1095	0.0658	0.0255	0.0160	0.0103
40	0.1460	0.0877	0.0340	0.0213	0.0137
50	0.1825	0.1096	0.0425	0.0267	0.0171
60	0.2190	0.1315	0.0510	0.0320	0.0205
70	0.2555	0.1534	0.0595	0.0373	0.0239
80	0.2920	0.1753	0.0680	0.0427	0.0273
90	0.3285	0.1973	0.0765	0.0480	0.0308
100	0.3650	0.2192	0.0850	0.0533	0.0342

Note:

These figures were derived by using Ohm's law and the above values for copper wire resistance.
The distances should be reduced to add safety factor, usually by about 20%, in order to make-up for losses due to connection deterioration, brownouts, system expansions, etc.