Can my existing electrical service handle EV chargers?

Enter the chargers you plan to install and your existing service rating and measured peak demand, and the calculator returns a GREEN / YELLOW / RED verdict: GREEN means the service has headroom, YELLOW means a compliant load-management system (EVEMS) can likely avoid an upgrade, and RED means a service upgrade is required. Results are a quick estimate for planning — double-check with your electrician and utility before building.

What size transformer do I need for an EV charging station?

The calculator sizes the transformer from the code load divided by a design loading factor (0.80 by default) and rounds up to the next standard kVA. As a rough guide, four 150 kW DC fast chargers draw roughly 645 kVA of input and point to a transformer in the 750–1000 kVA range; six 32 A Level 2 chargers at 208 V point to about 75 kVA. Confirm whether the transformer is utility- or customer-owned with your utility / LDC.

How is EV charging load calculated under the NEC (Article 625 / 220.57)?

Under the NEC, EVSE is a continuous load (Article 625), so the service/feeder calculation (Article 220, restructured into Article 120 in NEC 2026) applies a 7,200 VA per-EVSE minimum in the standard method and a 125% continuous-load factor for ampacity. The calculator follows this for the US profile; the exact provisions vary by adopted edition and occupancy.

How does CEC Section 86 handle EV charging load in Canada?

Under CEC 2024 Section 86, EVSE is treated as a continuous load (86-302 via 8-104). Without an EVEMS the chargers are counted at 100% under Section 8 — the former demand-factor table (Table 38) has been removed and is not relied on. With a compliant EVEMS, the EVSE demand can be limited to the EVEMS maximum under 8-106(10)/(11) with the EVEMS meeting 8-500. In Ontario, existing-service capacity may be assessed under 8-106(9) using the LDC 12-month peak plus the EVSE, per ESA Bulletin 86-1-7.

Can EVEMS load management avoid a service upgrade?

Often, yes. A listed/marked load-management system that monitors a compliant point can cap the EV load so the total stays within the existing service — frequently a far cheaper alternative to a service or transformer upgrade. The calculator compares the unmanaged code load against the EMS-limited load and highlights the capacity saved. The EMS only counts toward the code-managed figure when its listing and monitoring scheme are confirmed.

Is this a code-compliant load calculation I can submit for permit?

No — it’s a free estimate for early planning, not a permit document. Use it to scope the project and sanity-check feasibility, then confirm the final numbers with your electrician and utility before ordering equipment or building.

Planning tool

Commercial EV Charging Service Capacity & Transformer Calculator

Estimate EV charging load, service capacity, transformer size, switchboard rating and EMS load-management scenarios for North American commercial sites. Tell us the chargers you plan to install and see whether your service can take them — under the NEC (US) or CEC Section 86 (Canada).

Estimate your site

Describe the chargers and check your capacity.

Skip the existing-service step for a new-build estimate, or add it for a GREEN / YELLOW / RED verdict. Every result is shown on this page — no sign-up required.

1 · Chargers

What are you installing?

Charger group

Charger type Quantity

Rating per charger

Voltage Phase

Code reference Planned service Site type

Only charger quantity and rating are required — the rest is preset. Code reference sets the calculation profile (NEC for the US, CEC Section 86 for Canada).

2 · Optional

This calculator runs in your browser — please enable JavaScript, or contact our engineering team and we'll run the estimate for you.

Load & equipment by basis

Planning peak is a diversified operational estimate (for sizing storage / demand-charge studies) — it is not a code or AHJ load. Permit submissions use the unmanaged or EMS-limited code load.

Recommended equipment

Applicable references

Section numbering varies by adopted edition — verify with your AHJ / ESA.

Assumptions & notes

Next steps & submission package

— One-line diagram — stamped by a PE / P.Eng
— Load calculation (this report can serve as a draft)
— EVSE / EMS datasheets, NRTL safety listing (UL / cUL / CSA / ETL) & commissioning settings
— Service / transformer upgrade application (utility / LDC interconnection)
— Panel schedule, nameplates & equipment layout
— Local building / electrical permit
— ESA application / plan review (Ontario)

Considering storage to avoid a service upgrade?

Download the load report and request a BESS buffer analysis — we'll size the storage to your peak events and duty cycle (battery shaves short peaks; it does not indefinitely replace service capacity).

Configure a transformer Explore EV charging & power solutions

Save or send this report

Every number above is on this page. Print or save a PDF for your file, or share your project and we'll send a branded report and follow up within one business day.

Estimate only. These numbers are a quick planning estimate from your inputs and standard assumptions — handy for scoping and feasibility, not a permit or construction document. Real sizing depends on your site, the code edition your area has adopted and your utility, so double-check with your electrician and utility before ordering equipment or building.

Good to know

EV charging capacity, transformers & code

Common questions about sizing service, transformers and load management for commercial EV charging — for the US (NEC) and Canada (CEC Section 86 / Ontario ESA).

Can my existing electrical service handle EV chargers?: Enter the chargers you plan to install and your existing service rating and measured peak demand, and the calculator returns a GREEN / YELLOW / RED verdict: GREEN means the service has headroom, YELLOW means a compliant load-management system (EVEMS) can likely avoid an upgrade, and RED means a service upgrade is required. Results are a quick estimate for planning — double-check with your electrician and utility before building.
What size transformer do I need for an EV charging station?: The calculator sizes the transformer from the code load divided by a design loading factor (0.80 by default) and rounds up to the next standard kVA. As a rough guide, four 150 kW DC fast chargers draw roughly 645 kVA of input and point to a transformer in the 750–1000 kVA range; six 32 A Level 2 chargers at 208 V point to about 75 kVA. Confirm whether the transformer is utility- or customer-owned with your utility / LDC.
How is EV charging load calculated under the NEC (Article 625 / 220.57)?: Under the NEC, EVSE is a continuous load (Article 625), so the service/feeder calculation (Article 220, restructured into Article 120 in NEC 2026) applies a 7,200 VA per-EVSE minimum in the standard method and a 125% continuous-load factor for ampacity. The calculator follows this for the US profile; the exact provisions vary by adopted edition and occupancy.
How does CEC Section 86 handle EV charging load in Canada?: Under CEC 2024 Section 86, EVSE is treated as a continuous load (86-302 via 8-104). Without an EVEMS the chargers are counted at 100% under Section 8 — the former demand-factor table (Table 38) has been removed and is not relied on. With a compliant EVEMS, the EVSE demand can be limited to the EVEMS maximum under 8-106(10)/(11) with the EVEMS meeting 8-500. In Ontario, existing-service capacity may be assessed under 8-106(9) using the LDC 12-month peak plus the EVSE, per ESA Bulletin 86-1-7.
Can EVEMS load management avoid a service upgrade?: Often, yes. A listed/marked load-management system that monitors a compliant point can cap the EV load so the total stays within the existing service — frequently a far cheaper alternative to a service or transformer upgrade. The calculator compares the unmanaged code load against the EMS-limited load and highlights the capacity saved. The EMS only counts toward the code-managed figure when its listing and monitoring scheme are confirmed.
Is this a code-compliant load calculation I can submit for permit?: No — it’s a free estimate for early planning, not a permit document. Use it to scope the project and sanity-check feasibility, then confirm the final numbers with your electrician and utility before ordering equipment or building.