How to keep the public off your chargers
Require authentication. In an open parking lot, an RFID whitelist or app authorisation is the only mechanism that reliably stops a stranger charging, because it is the only one that physically withholds electricity from someone who has not been approved. Signage stops nobody. Pricing filters casual users but does not exclude anyone willing to pay. A gate or a controlled garage works, but only if you already have one — building one to protect four charging ports is almost never worth it. There is one trap that catches properties after the fact: if the chargers were funded by a public-access incentive program, the agreement may contractually require you to keep them open to the public for a defined term, and restricting them later can put the money at risk. Check the funding agreement before you change the access rules.
Updated 2026-08-20
The four mechanisms, ranked by whether they work
Only one of these actually withholds energy from an unapproved driver. The other three shape behaviour, which is a different and weaker thing.
| Mechanism | Stops an unapproved driver? | Ongoing cost | Where it fits |
|---|---|---|---|
| RFID whitelist on a networked charger | Yes | Per-port subscription | Residents, employees, tenants — a known, stable list |
| App or account authorisation | Yes | Per-port subscription | Guests and rotating users you can enrol quickly |
| Price set high enough to deter | No — anyone willing to pay gets in | Subscription plus transaction fees | Managing demand, not access |
| Physical barrier: gate, garage, arm | Yes | Whatever the barrier already costs you | Only where the barrier already exists |
| Signage: 'residents only', 'customers only' | No | The cost of the sign | Sets an expectation; enforcement is a separate question |
| Time limits and idle fees | No — controls dwell, not identity | Subscription | Stopping one car occupying a port all day |
| Wheel stops, cones, chains across the stall | Partially, and badly | Staff time, plus a liability question | Not recommended — see below |
Why signage does not work, even when it is legally backed
A sign changes what people are supposed to do. It does not change what the port does when someone plugs in.
The incentive trap: you may have promised public access
Programs that pay for chargers frequently buy something in return, and what they usually buy is public availability for a defined term.
Two-tier access is usually the better goal than exclusion
Most properties do not actually want the public excluded. They want the public to stop charging free, and residents or employees to get priority.
| User group | How they are identified | What they pay | Restrictions |
|---|---|---|---|
| Residents or employees | RFID card or enrolled app account | Your internal rate, or free | Usually none |
| Guests and visitors | App account or contactless payment | Public rate | Time limit and idle fee |
| Everyone else | App account or contactless payment | Public rate, set above local alternatives | Time limit and idle fee |
| Unapproved, on a restricted-only site | Not identified | No session starts | Excluded |
What to do if the chargers are already installed and unnetworked
You have three options and they cost very different amounts, so establish which hardware you actually own before deciding.
Can we just put up a sign saying residents only?
You can, and it will not stop anyone whose car accepts the connector. A sign changes the rule, not the equipment's behaviour. Many states do have laws about parking in designated EV charging spaces, sometimes with towing authority, but those address vehicles occupying the space rather than a driver who genuinely charges there. If you need exclusion, you need authentication.
Will setting a high price keep the public away?
It filters casual users and it will not exclude anyone. Price is a demand tool, not an access tool. It is genuinely effective at a different problem — stopping your ports being the cheapest electricity in the area and attracting drivers who have no other reason to be on your property. Combine a public rate with a lower resident or employee rate and you get priority without exclusion.
Does taking a rebate mean we have to let the public charge?
Sometimes, and it is written in the agreement rather than implied. Federally funded charging under 23 CFR Part 680 carries formal public-availability requirements. State and utility programs often impose their own public-access term, a minimum operating period, and a clawback if you fall short. Read the agreement for 'publicly accessible', 'availability' and 'clawback' before you change anything, and ask the administrator in writing if it is ambiguous.
How do we stop one car occupying a charger all day?
An idle fee that starts after the session completes, plus a posted time limit. Both need networked hardware, because both depend on the system knowing when charging finished and who was plugged in. Give a generous grace period — an hour is common and easy to defend — and post the rule at the stall so the first person to be charged is not surprised.
Can we lock the connector when the property is closed?
Networked hardware can schedule availability, so the ports simply refuse to start a session outside your hours. That is cleaner than a physical lock, which creates an object the public interacts with and a maintenance item nobody remembers. If you have unnetworked equipment, a scheduled contactor upstream of the chargers can accomplish something similar — ask your electrician, and make sure it cannot interrupt a session mid-charge.
Is restricting access worth losing the utility incentive?
Rarely, and the arithmetic is usually available to you. Compare the incentive amount, plus any clawback exposure, against the electricity that non-approved users actually consume — which you can measure at the meter serving the chargers over one month. Properties tend to argue this from irritation rather than from the meter reading, and the meter reading is often much smaller than the irritation.
- eCFR — 23 CFR Part 680, National Electric Vehicle Infrastructure Standards and Requirements (availability, payment and uptime obligations for federally funded charging)
- US DOE Alternative Fuels Data Center — state laws and incentives index (EV charging space laws by state)
- Open Charge Alliance — OCPP protocol and certification program
Decide access before you decide hardware
Access rules change what equipment you can buy and which funding you can accept. Tell us who the ports are for, how many you need and where the power is, and the estimate gives you a range for the install that supports it.