Electricity distribution scorecard

A quick look at how New Zealand's electricity lines companies (EDBs) compare on cost, reliability, losses and looking after their assets, allowing for how big and how spread out each network is.

29 EDBs
Data 2021–2025
Updated 5 October 2026
All the data (ZIP, 26 KB)
Method

Scores at a glance

Score: Out of 100, where 100 is best and 50 typical. Size and density are allowed for.
Band: The range covers the middle 90% of ranks as we randomly vary the four dimension weights. Strong or Weak means that whole range stays in the top or bottom third.
Groups: Thirds by ICPs per km of line: sparse below 7.5, intermediate 7.5–12.6, dense 12.6+.

Scroll the table sideways for the scores.

Scores out of 100, higher is better, compared with all EDBs, grouped by network density
EDB	√(ICPs×km)	ICPs/km	Overall	Band (rank range)	Cost25%	Reliability25%	Utilisation and losses25%	Asset management25%
Sparse below 7.5 ICPs/km
OtagoNet OtagoNet Poor-condition grades likely on the wrong scale: Pole Mounted Transformer 2024 (0.32% vs usual 39%); Wood poles 2025 (0.0042% vs usual 24%). Without those years: asset score 32 (not 34), rank unchanged.	9,477	4.2	74	Strong 1–5	80	84	96	34
The Power Company The Power Company Poor-condition grades likely on the wrong scale: Wood poles 2025 (0.011% vs usual 24%). Without those years: asset score about the same, rank unchanged.	18,210	4.2	70	Strong 1–4	80	75	70	54
Scanpower Scanpower No zone substations: takes supply from Transpower at distribution voltage, so step-down losses and costs sit upstream. Flatters its loss ratio and cost.2025 loss ratio 0.4% vs usual 7.3%: implausible, likely a disclosure error. Scored on the five-year median, so no effect.	2,664	6.4	63	Strong 4–8	71	82	43	56
Centralines	4,120	4.9	57	Middle 6–15	88	41	41	57
Network Waitaki	5,052	7.0	52	Middle 7–20	27	84	48	49
The Lines Company	10,326	5.4	50	Middle 9–19	38	41	57	64
Firstlight Network	10,119	6.5	49	Middle 8–25	88	7	45	56
EA Networks	8,062	6.6	43	Middle 10–27	12	91	18	51
Buller Electricity	1,767	7.4	39	Middle 19–27	21	16	59	58
Westpower	5,601	6.4	29	Weak 25–29	16	57	16	26
Intermediate 7.5–12.6 ICPs/km
Powerco	101,624	12.3	66	Strong 1–6	82	68	50	64
Network Tasman	12,504	11.3	60	Middle 4–15	98	62	46	32
Northpower	19,718	10.2	53	Middle 5–21	57	11	64	79
Waipa Networks Waipa Networks Poor-condition grades likely on the wrong scale: Distribution OH Open Wire Conductor 2024 (0.027% vs usual 4%); Distribution OH Open Wire Conductor 2025 (0.027% vs usual 4%). Without those years: asset score 45 (not 49), rank 17 (not 16).No zone substations (has 33 km of subtransmission): takes supply from Transpower at distribution voltage, so step-down losses and costs sit upstream. Flatters its loss ratio and cost.	8,145	12.4	50	Middle 9–23	75	12	62	49
Horizon Networks	8,132	9.7	45	Middle 12–26	77	27	29	48
Alpine Energy	12,118	7.7	45	Middle 10–26	11	84	48	36
MainPower NZ	15,129	8.4	42	Middle 18–26	54	43	32	38
Marlborough Lines	9,669	7.7	39	Middle 16–27	7	70	48	30
Top Energy	11,873	8.0	26	Weak 27–29	16	0	43	46
Dense 12.6+ ICPs/km
Nelson Electricity Nelson Electricity 91% underground. Reliability isn't adjusted for undergrounding, so the score keeps any benefit; the capital cost is in totex via a RAB of $30,653 per √(ICPs × km) (median $25,103).	1,662	31.3	69	Strong 2–5	77	86	70	45
Orion NZ	50,920	18.4	60	Middle 3–14	46	100	43	53
Wellington Electricity	28,949	35.9	56	Middle 7–17	73	79	38	37
Unison Networks	33,238	12.6	51	Middle 7–18	54	29	73	50
WEL Networks	23,575	17.4	50	Middle 10–17	45	39	62	55
Electra	10,482	19.5	50	Middle 12–17	50	43	59	49
Electricity Invercargill Electricity Invercargill 92% underground. Reliability isn't adjusted for undergrounding, so the score keeps any benefit; the capital cost is in totex via a RAB of $32,064 per √(ICPs × km) (median $25,103).	3,416	26.4	46	Middle 16–22	54	30	59	43
Aurora Energy	24,298	15.0	40	Middle 15–27	5	39	43	74
Vector Lines	108,422	31.1	39	Weak 22–25	23	36	43	54
Counties Energy	12,880	13.2	37	Weak 21–28	25	14	45	63

· 50 is typical · click an EDB for its detail

What stands out

The top is fairly settled. OtagoNet, The Power Company, Nelson Electricity, Powerco and Scanpower are in the top quarter almost whatever the weighting (97–100% of weightings), and no one beats any of them on everything.
The bottom is pretty settled. Westpower and Top Energy stay in the bottom five however you weight the scores (at least 95% of weightings), and 9–15 EDBs do better than each of them on everything.
Most are too close to call. Only 5 EDBs stay in the top third and 4 in the bottom third across the middle 90% of weightings. The other 20 overlap too much to put in order (a typical rank range is 9 places), so treat them as a group.
A good overall score can hide a weak spot. OtagoNet (asset management 34) and Northpower (reliability 11) rank in the top half but have one area 30+ points below their overall score. Averaging lets the strong areas cover for it.
Most all-round. The Power Company has no weak spot: its lowest score is 54 (asset management). Every other top-ten EDB has something at 50 or below.

One EDB against the rest

EDB

OtagoNet

OtagoNet Sparse networks: 4.2 ICPs per km, 19,312 ICPs, 4,653 km of circuit, 5.5% underground.Consumer trust (via TPCL); price-quality regulated.In the top quarter in 100% of weightings; no EDB beats it on everything.Poor-condition grades likely on the wrong scale: Pole Mounted Transformer 2024 (0.32% vs usual 39%); Wood poles 2025 (0.0042% vs usual 24%). Without those years: asset score 32 (not 34), rank unchanged.

overall: 74 rank 1 of 29
band (rank range): Strong 1–5
sparse networks: 67 rank 1 of 10

OtagoNet other EDBs median top quarter of all EDBs typical for its size and density (1.00×) better →

Cost80

Opex per ICP

$555 as disclosed · log scale

0.67×percentile 100

Totex with capital services per √(ICPs × km)

$3,922 as disclosed · log scale

0.96×percentile 61

Reliability84

Unplanned SAIDI (class C)

204 min as disclosed · log scale

0.56×percentile 86

Unplanned SAIFI (class C)

2.11 as disclosed · log scale

0.67×percentile 82

Utilisation and losses96

Loss ratio

3.9% as disclosed · log scale

0.81×percentile 100

Maximum demand ÷ distribution transformer capacity

0.28 as disclosed · log scale · capped at 0.4

1.17×percentile 93

Asset management34

Assets installed before 1980 (45+ years old)

2025 disclosure

23.5%percentile 71

Assets in poor condition (grades H1–H2)

11.5%percentile 14

Renewal capex ÷ network depreciation

capped at 1.5

0.95percentile 43

Totex forecast error

17.9% as disclosed · log scale

1.68×percentile 7

Values for every EDB (adjusted)

Values as scored for every EDB and scored measure
EDB	Opex /ICP	Totex /unit	Unplanned SAIDI	Unplanned SAIFI	Losses	Demand ÷ capacity	45+ years old	Poor condition	Renewal ÷ depn	Forecast error
OtagoNet	0.67×	0.96×	0.56×	0.67×	0.81×	1.17×	23.5%	11.5%	0.95	1.68×
The Power Company	0.71×	0.94×	0.53×	0.87×	1.00×	1.41×	32.6%	3.8%	0.82	0.55×
Nelson Electricity	0.77×	0.96×	0.56×	0.56×	0.94×	1.06×	39.6%	0.3%	0.56	0.85×
Powerco	0.83×	0.89×	0.76×	0.74×	1.00×	1.02×	25.7%	5.9%	1.22	0.68×
Scanpower	0.91×	0.91×	0.73×	0.42×	0.96×	0.94×	9.7%	9.9%	1.04	1.03×
Orion NZ	1.04×	1.00×	0.29×	0.37×	0.93×	0.89×	28.7%	1.3%	0.72	0.89×
Network Tasman	0.70×	0.66×	0.77×	0.81×	1.09×	1.06×	37.1%	1.7%	0.85	1.99×
Centralines	0.83×	0.81×	0.99×	1.22×	0.95×	0.90×	30.5%	5.3%	1.50	0.98×
Wellington Electricity	0.87×	0.92×	0.61×	0.72×	1.12×	1.05×	43.2%	5.0%	0.96	1.06×
Northpower	1.13×	0.85×	1.99×	2.35×	0.96×	1.06×	23.8%	4.3%	1.50	0.60×
Network Waitaki	1.21×	1.10×	0.46×	0.73×	0.97×	0.99×	24.8%	5.5%	1.26	1.58×
Unison Networks	1.00×	0.97×	2.30×	0.98×	0.84×	1.00×	26.0%	13.3%	1.34	0.91×
WEL Networks	1.03×	1.06×	1.20×	1.14×	0.92×	1.00×	26.2%	0.4%	0.98	1.25×
Electra	1.04×	0.97×	0.87×	1.29×	1.06×	1.11×	30.6%	3.5%	1.09	1.17×
The Lines Company	1.06×	1.08×	1.04×	1.18×	1.11×	1.22×	28.2%	3.0%	1.19	0.87×
Waipa Networks	0.95×	0.83×	2.02×	1.46×	0.91×	0.99×	11.7%	4.2%	0.85	1.70×
Firstlight Network	0.83×	0.82×	2.63×	2.02×	1.13×	1.07×	32.3%	7.3%	1.50	0.75×
Electricity Invercargill	0.93×	1.06×	1.15×	1.38×	1.06×	1.14×	31.5%	14.5%	1.03	0.62×
Horizon Networks	0.89×	0.86×	1.41×	1.35×	1.02×	0.91×	28.2%	7.6%	0.88	0.67×
Alpine Energy	1.39×	1.13×	0.72×	0.50×	0.85×	0.80×	32.7%	18.9%	1.50	1.08×
EA Networks	1.18×	1.48×	0.42×	0.62×	1.49×	0.96×	5.8%	4.1%	0.70	1.26×
MainPower NZ	0.97×	0.98×	1.40×	0.91×	0.95×	0.80×	20.1%	11.1%	0.72	1.16×
Aurora Energy	1.37×	1.17×	0.93×	1.34×	1.10×	1.05×	23.8%	6.4%	1.50	0.61×
Marlborough Lines	1.30×	1.22×	0.73×	0.78×	0.82×	0.79×	26.4%	10.8%	0.63	1.03×
Vector Lines	1.06×	1.17×	1.49×	1.13×	0.98×	0.97×	23.2%	4.8%	1.12	1.57×
Buller Electricity	1.24×	1.11×	2.00×	1.40×	0.86×	0.95×	26.9%	2.5%	0.76	0.72×
Counties Energy	1.12×	1.15×	1.59×	2.21×	0.92×	0.86×	9.4%	7.6%	1.50	1.24×
Westpower	1.33×	1.13×	0.87×	0.90×	1.19×	0.92×	11.8%	24.7%	0.40	1.40×
Top Energy	1.22×	1.17×	3.59×	2.42×	1.33×	1.09×	22.7%	8.1%	0.70	0.90×

What good looks like

Scroll the table sideways for the density groups.

What good looks like, as disclosed, by density group
Measure	All EDBs29 EDBs	Sparse networksbelow 7.5 ICPs/km, 10 EDBs	Intermediate networks7.5 to below 12.6, 9 EDBs	Dense networks12.6 ICPs/km and above, 10 EDBs
Cost
Opex per ICPlower is better	$553 / $399	$726 / $587	$551 / $472	$384 / $296
Totex with capital services per √(ICPs × km)lower is better	$4,353 / $3,815	$4,197 / $3,826	$3,770 / $3,628	$4,569 / $4,311
Reliability
Unplanned SAIDI (class C)lower is better	170 min / 98 min	199 min / 113 min	212 min / 149 min	94 min / 39 min
Unplanned SAIFI (class C)lower is better	1.62 / 1.13	1.86 / 1.29	1.77 / 1.42	1.16 / 0.54
Utilisation and losses
Loss ratiolower is better	5.0% / 4.5%	6.9% / 5.1%	5.2% / 4.8%	4.6% / 4.1%
Maximum demand ÷ distribution transformer capacityhigher is better	0.27 / 0.29	0.25 / 0.28	0.26 / 0.27	0.30 / 0.35
Asset management
Assets installed before 1980 (45+ years old)lower is better	26.2% / 23.2%	25.8% / 14.7%	25.7% / 22.7%	27.5% / 24.4%
Assets in poor condition (grades H1–H2)lower is better	5.5% / 3.8%	5.4% / 3.9%	7.6% / 4.3%	4.9% / 1.8%
Renewal capex ÷ network depreciationhigher is better	0.98 / 1.26	0.99 / 1.24	0.85 / 1.22	1.06 / 1.29
Totex forecast errorlower is better	9.0% / 7.0%	11.8% / 8.8%	10.1% / 6.4%	7.9% / 6.3%

· median / top quarter, 2021–2025 · better →

Method

Not an efficiency benchmark. It shows where each EDB sits among the others on public data. Anything the adjustments miss, like terrain, weather or history, still shows up in the scores.
What’s compared. 10 measures in four groups: cost, reliability, losses and transformer use, and asset management. Each is the EDB’s figure over 2021–2025 (asset age is a 2025 snapshot), in real dollars of the year to June 2025 (CPI).
Size and density. Cost, reliability, losses, transformer use and forecast error are compared with what a typical EDB with the same number of connections and km of line gets. Losses and transformer use also allow for energy used per connection.
Scores. Each measure becomes a percentile out of 100 (higher is better). A group’s score is the average of its measures, and the overall score the average of the four groups. Transformer use above 0.4 and renewal above 1.5× depreciation score the same as the cap.
Ranges and bands. The overall score is rerun with 10,000 random weightings of the four groups; the range is the middle 90% of ranks. Strong or Weak means the whole range is in the top or bottom third.
Density groups. Thirds by connections per km of line, so you can compare like with like.
Data. Commerce Commission, electricity distribution information disclosures (CC BY 4.0). Figures are derived and adjusted by NZ Infrastructure Insights and are not endorsed by the Commission. Everything is in the ZIP, with a readme of the sources and columns.