Heater Finder

Square D melting alloy thermal units (heaters) · Type S and other Square D starters

1Starter

Catalog number from the nameplate (optional)

or choose it

Starter family

Type and NEMA size

Type and Series are on the starter nameplate. Series only matters where it is listed.

Size

Size 1Size 2

2Motor

Motor nameplate full-load amps (FLA)

Motor voltage Motor HP

Schneider Table 16.370 approximate currents. Recheck against the nameplate at installation.

Service factor

1.15 – 1.25 1.0

Heaters in the overload relay

1single phase 22-phase / some 1ϕ 3three phase

Overload relay mounted in

Large enclosureSmall enclosure

Trip class

StandardClass 20 · B, CC QuickClass 10 · FB SlowClass 30 · SB

Motor vs. starter ambient temperature

✓Heater selection

Choose the starter and enter the motor FLA to see the heater.

?What does this heater fit?

Heater (thermal unit) number

Type the number printed on the heater. It shows every Square D starter and size the heater is listed for, with the motor FLA it covers.

Scan to open the Heater Finder on your phone.

On a phone, use Add to Home Screen to keep it like an app. It works offline after the first visit.

https://capital-heater-finder.pages.dev/

Data source: Schneider Electric Digest 179, Section 16: NEMA and Definite Purpose Contactors and Starters (0100CT2401-SEC-16), Thermal Unit Selection, pages 16-136 to 16-160. Selections follow Schneider's procedure: 100% of FLC for 1.15–1.25 service factor motors, 90% for 1.0. This tool is a selection aid. Confirm against the heater table inside the starter cover or the Digest before installing. For devices not listed, including obsolete starters, Schneider's Customer Care Center is 1-888-778-2733.

Questions? Kevin Fleming, Application Engineer, Capital Electric A&C Team · kevin.fleming@capitalelectricsupply.com

Rev 1 · November 2026 · Capital Electric · A&C Team

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