A load calculation is the math the electrician and the inspector use to decide whether your existing panel can take a new circuit. It is not adding nameplates in a column and hoping. In San Diego County it shows up before an EV charger, a range swap, an ADU feeder, or a panel upgrade. Bright Pro Electric matches you with a licensed electrician. We do not stamp the calculation.
The on-site planning tool at panel load calculator is a conversation starter. It is not the permit document. The electrician who pulls the permit owns the method the reviewing department will accept.
What a load calculation is actually answering
Can this service and this panel feed the loads that will run together, under the method the adopted code allows? The answer is yes, yes with a listed load-management device, yes with a subpanel, or no, replace the service equipment.
NEC 220.87 is a standard-practice method this site is allowed to name for adding load to an existing installation. It is a method. This page does not attach a numeric result, a percent headroom, or a worked example that pretends to be your house. Other Article 220 methods exist. The electrician picks the one the authority having jurisdiction will accept for that permit.
Do not use an SDG&E bill as the calculation. Demand on a bill does not by itself prove the service is undersized or that it has room.
Do not add every nameplate and call that the load. Continuous loads, demand factors, and existing measured demand are why the method exists.
When San Diego jobs hit it
EV chargers on 100-amp services in older El Cajon, La Mesa, and Lemon Grove houses (high pre-1978 stock) hit it first. So do induction ranges in North Park remodels, heat-pump water heaters, and ADU feeders in unincorporated Lakeside and Ramona.
Coastal Carlsbad and Encinitas tracts with 200-amp services still need the calculation when solar, a charger, and a spa land on the same can. Service size on the cover is not spare capacity.
If the panel is physically full of slim breakers, that is a tandem breaker question and a label question. Slots and calculated load are two different gates. You can have empty slots and no calculated room. You can have calculated room and no listed slot.
SDG&E reviews added load on service upgrades through its service-planning process. This site does not publish a utility timeline. Do not state one.
Permits, fees, and who signs it
The calculation travels with the electrical permit. City of San Diego Development Services, County PDS for unincorporated parcels, Poway Building Services, and each city’s department review their own packages.
A panel upgrade to 200 amps in the City of San Diego is a published Simple or Plan permit at $176.57 on the City electrical schedule. Adding the first five 15- to 45-amp circuits is the same $176.57 Simple figure. Unincorporated County electrical-only is $392 on PDS-613 effective 07/10/2026. Those are permit fees. They are not the cost of the upgrade.
The electrician pulls the permit when that is in the written scope. Bright Pro Electric does not. Check the business on the CSLB license lookup. C-10 is the electrical classification.
The 2025 California Electrical Code took effect January 1, 2026. Local amendments apply. The calculation follows the edition the city is enforcing.
What belongs in the written proposal
Ask which method they will use. Ask whether they will measure existing demand if 220.87 is the path. Ask what happens if the numbers fail: load management, subpanel, or service upgrade, as separate prices. A single “panel looks fine” line is not a calculation.
For upgrade cost drivers already published on this site, see panel upgrade cost in San Diego and when to upgrade your electrical panel.
Frequently asked questions
Can I do my own load calculation for a permit?
Owner-builders can file some City of San Diego electrical permits. The calculation still has to be a method the reviewer accepts. A hired electrician should not hide behind a homeowner worksheet. Get the method in the contract.
Does NEC 220.87 mean I can skip a panel upgrade?
It means existing demand may be used instead of a full nameplate add, when the method’s conditions are met. It does not promise room. The electrician still has to show the numbers.
Is the website calculator official?
No. It is a planning aid. The permit package is the official math.
When to call us
Call before you buy the charger, the range, or the ADU panel, not after the equipment is on the driveway. Call (858) 988-5580. Hours are Monday through Saturday, 7am to 7pm. After hours, leave a message on the contact page. We match you with an independent licensed electrician. We do not certify the load.