How stress is measured. For ERCOT and CAISO, stress = current demand ÷ live available generating capacity published by the operator. For MISO, SPP, NYISO and ISO-NE (which don't publish live capacity openly), stress = current demand ÷ that region's all-time peak demand record, a rough proxy for how close the system is to its historic limits. These six operators publish new numbers every 5 minutes. The other eight regions - Mid-Atlantic (PJM), Southeast, Florida, Carolinas, Tennessee Valley, Kentucky, Northwest & Rockies and Southwest - use hourly demand from the U.S. Energy Information Administration's EIA-930 survey, which usually runs 1–2 hours behind (sometimes 3; each card says how far). Their stress = demand ÷ the region's all-time EIA-930 demand record, with the month it was set on the card. The page itself refreshes every 60 seconds. Power sources show the operator's latest generation mix for the six live operators. For the EIA regions the mix is yesterday's 24-hour average from EIA's daily data, not live. "Carbon-free" counts solar, wind, hydro and nuclear, and negative values (batteries charging, net exports, or plants drawing power while idle, like solar at night) are left out of the bar and listed separately. Prices are real-time wholesale prices at a major trading hub, in dollars per megawatt-hour - not what households pay. Mid-Atlantic (PJM) shows the load-weighted average of PJM's zonal prices from pjm.com's public price map; Northwest and Southwest show load-weighted Western Energy Imbalance Market prices for their utilities. Regions without a wholesale market, where local utilities set rates, show no live price. Grid status is each operator's own published condition (normal, advisory, watch, warning or emergency); the five EIA-only regions don't publish one. Carbon intensity is the fuel mix × direct-combustion CO₂ factors. For the EIA regions it is an estimate from a fuel mix about a day old, and the cleanest window repeats yesterday's pattern; for the six live operators it uses their wind and solar forecasts. Hazards are National Weather Service alerts, NHC storms, large wildfires (NIFC) and space weather (NOAA SWPC) that touch each region. Best times come from each operator's demand forecast (EIA-930's day-ahead demand forecast for the EIA regions); where a forecast stops short of 24 hours, the rest follows today's actual pattern. All times are shown in the region's local time. Sources: ERCOT, CAISO Today's Outlook, MISO, SPP, NYISO, ISO New England, PJM public feeds · U.S. Energy Information Administration (EIA-930, EIA-860M) · NOAA NWS, NHC and SWPC · NIFC · USGS · weather via Open-Meteo. This product uses the FCC Data API but is not endorsed or certified by the FCC. GridPulse is not affiliated with any grid operator, and its numbers are not for operational or safety decisions.