TNUoS (Transmission Network Use of System)
TNUoS charges cover the cost of the high-voltage grid that carries power from generators to local networks.
What it is
TNUoS stands for Transmission Network Use of System. It is the charge for the high-voltage transmission network that carries power from generators towards the local networks. It is one of the non-commodity charges in your electricity bill, alongside DUoS and BSUoS.
Where you will see it
- For many small sites, built into the daily standing charge or the unit rate, so it is not shown as a line item.
- For larger sites with agreed capacity, as a separate line or in the contract's cost breakdown.
Why it matters
For smaller meters, the charge is mostly fixed and based on meter type and consumption band, with part based on use in peak periods. For larger half-hourly sites, part of the charge has traditionally been linked to demand at winter peak times, often called triads. For most small businesses the charge is largely a fixed cost, and it varies by region.
Check how your quote treats it. Whether it is fixed into the price or passed through at cost changes your risk, as explained in pass-through vs fixed charges.
Example
Two offices on identical contracts can see different standing charges because they sit in different regions. Part of that gap is network charging. Our guide on why standing charges vary by region covers this in more depth.
Related terms
For a plain overview see what are TNUoS and DUoS charges.
Common questions on this topic
Sources
General information only. Energy prices, rules and supplier terms change; check the latest position with your supplier, Ofgem or the Energy Ombudsman before you act.