NEM transmission line loading map: where the grid has room

A live dashboard of Australia's National Electricity Market, built with NEM Explorer and refreshed from AEMO data on every view · updated 4 November 2026

Transmission line loading

How hard each NEM transmission line works against its rating, and which way power flows along it. Each line is drawn straight from bus to bus and coloured from blue (lightly loaded) to red (at its rating). An arrow shows the way power flows at least 70% of the selected hours; a dot means it flows both ways.

Siting a load or a generator. A new load relieves a busy line when it connects at the end power flows away from, because it uses power that would otherwise leave along that line. At the end power flows into, it adds to the line. A new generator is the other way round. Pick the season and hours that matter for your project: a solar-soaked midday and a winter evening load the network very differently.

Selected period

Figures as of 8 November 2026, 1:43 am NEM time.

594 lines carrying power
15.59% median average loading
93.6% of them average under 30%
6 lines idle all period
91 lines with no map position

Line loading and usual flow direction

Colour follows the 'Colour lines by' choice; hover a line's midpoint for all three measures and its usual direction. Zoom with the buttons at top right.

line	loading_pct
HGTS_TRTS1_500: Haunted Gully TS 500kV – Tarrone 500kV (500 kV)	0
GTS_PTH1_220: Geelong 220kV – Point Henry 220kV (220 kV)	0
GTS_PTH2_220: Geelong 220kV – Point Henry 220kV (220 kV)	0
GNTS_SHTS3_220: Glenrowan 220kV – Shepparton 220kV (220 kV)	0
DDTS_SHTS_220: Dederang 330kV – Shepparton 220kV (220 kV)	0
FA_QU_SR_HM: Farrell – Hampshire (110 kV)	0.04652
FA_QU_SR_HM: Farrell – Savage River (110 kV)	0.04652
FA_QU_SR_HM: Farrell – Que (110 kV)	0.04652
FA_QU_SR_HM: Farrell – Waratah Tee (110 kV)	0.04652
BU_HM: Burnie – Hampshire (110 kV)	0.05039
GT_TV1: George Town – Tamar Valley PS (110 kV)	0.104
0X1: Buronga 220kV – Red Cliffs 220kV (220 kV)	0.6072

Net power leaving each substation

Red substations send power out over their lines on average (local generation exceeds local load); blue ones draw it in. Load placed at a red one uses power that would otherwise travel away.

substation	net_out_mva
Sydney West 330kV	-1,296
Boyne Island 275kV	-865.7
Sydney South 330kV	-860.9
Tomago 330kV	-849.1
Sydney North 330kV	-799.7
Heywood 500kV	-625.4
Bouldercombe 275kV	-467.9
Newcastle 330kV	-463.9
Rowville 500kV	-403.9
South Pine 275kV	-371.1
Cranbourne 220kV	-356.2
George Town	-315

Substations sending out the most power

Where a new load would soak up local surplus. Power station switchyards lead the list: the lines out of them were built to carry their output, and the room grows as stations retire.

Line loading by hour of day

Across the lines selected, ignoring the hour filter. The 90th-percentile line shows how hard the busier lines work at each hour.

hour_of_day	median_line_loading_pct	p90_line_loading_pct
0	14.53	25.36
1	14.23	24.87
2	14.1	24.74
3	13.97	24.75
4	14.14	24.78
5	14.43	24.95
6	14.63	26.53
7	15.31	29.05
8	15.46	30.45
9	14.93	31.65
10	14.69	31.61
11	14.47	31.33

Lines by average loading

The 50 lines at the end of the range set by 'Line table'. Lines that never reached 1% of their rating (out of service, or idle) are left out.

Method

Loading is the measured MVA flow on each line end as a percentage of the NORM real-time rating AEMO's dispatch engine applied in the same 5-minute interval. That rating already moves with the weather and the season. Both come from the SCADA inputs of AEMO's NEMDE case files, from July 2009. A line measured at both ends takes the higher end. Average loading is over the selected days, season and hours. A line that never reached 1% of its rating in the period counts as idle: out of service, or connected but carrying nothing.
Direction is the share of those intervals in which power flowed from one end to the other. The readings are snapshots taken just before each interval starts, not interval averages.
Net power out of a substation sums the average flow out along each of its lines, in MVA (apparent power, close to MW on transmission lines). It counts lines only, not transformers.

Caveats

Lightly loaded is not spare capacity. AEMO keeps the system secure against any credible contingency, such as losing a line. Parallel circuits can be at their limit while each carries about half its rating, because if one trips the other takes the flow. Treat a lightly loaded line as a lead to check against binding network constraints and a connection enquiry, not as proof of headroom.
Data trails real time by one to two months, because AEMO publishes each month of case files about four weeks after it ends.
Lines are straight bus-to-bus segments, not their real routes. A tee'd line is drawn as branches from one end. Lines whose substations have no known position are counted above but not drawn.
Distribution networks below about 66 kV are not in the data.

Sources: AEMO NEMDE case files and network equipment tables; substation positions from AEMO's network map and Electricity Infrastructure, © Commonwealth of Australia (Geoscience Australia) 2026, CC BY 4.0.

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