Thermal relay pricing on the open market is bimodal: entry-level three-phase units on Made-in-China.com list from US$2.00 per piece at 100-piece MOQ [S2][S4], while sealed, high-power or fully certified industrial assemblies reach US$1,000 per set at 5-set MOQ [S4].
For 2026 buyers the spread is governed less by the heating bimetal itself than by certification stack, trip-class, current range, and whether the unit is sold bare or as a contactor-mounted motor-protection module. The TECO RHU & RHN Series — three-phase, contactor mount, 0.1–38 A trip, IEC + China GB compliant, CSA / UL / CE / RoHS marked, trip class 10A, manual or automatic reset — sits in the upper mid-tier [S1].
Price tiers on Made-in-China.com (June 2026 snapshot)
Three observable bands dominate the Made-in-China.com catalog for "Thermal Over Load Relay" and related thermal relay searches [S4][S5]. The lowest band — US$2.00–3.00 per piece at 100-piece MOQ — covers household-grade, single-phase, AC, three-pole units described as "medium power" with no premium certifications advertised [S2][S4]. The mid-band clusters around nameplate products such as the Lrd33 / Lrd16 (Schneider Electric–pattern references) with CE certificates noted as "contact issuer for current status," typically sold in lots of 100 pieces [S2][S5]. The high band — US$1,000 per set at 5-set MOQ — lists sealed construction, AC/DC power source, and "high power" contact load ratings, with selling-unit dimensions around 75×80×80 cm implying frame-size contactor pairing rather than DIN-rail standalone [S4].
For a 3-phase motor-protection use case, the published TECO RHU & RHN Series spec sheet anchors the upper mid-tier technically if not in headline price: 0.1–38 A adjustable trip, phase-failure protection, trip class 10A, IEC + China GB compliance, with CSA, UL, CE, RoHS certificate stack [S1]. Most catalog pages do not publish list price, routing inquiries through RFQ; the Made-in-China.com spread above is therefore the cleanest public reference for 2026 budget work.
What drives the cost: a four-axis breakdown
Spec-to-price correlation on thermal relays breaks into four decision axes, each with measurable cost leverage. First, current range — 0.1–38 A in the TECO RHU/RHN bracket is the broadest "general-purpose" window for fractional to mid-horsepower motors [S1]; wider ranges (e.g. 100 A+) require larger heating elements and command higher unit prices. Second, trip class — class 10A on TECO's datasheet is the standard fast-trip curve; class 20 or 30 (heavy-start, high-inertia loads) typically carries a 10–20% premium because of heavier bimetal mass and recalibrated heaters. Third, certification stack — IEC + GB + CE is the baseline for cross-border shipment; adding UL and CSA (as on the RHU/RHN) addresses North American panels and lifts the unit into the brand-name tier [S1]. Fourth, mounting and reset topology — contactor-mount (plug-in to a specific contactor family) versus DIN-rail standalone; manual reset versus automatic reset is a feature flag rather than a price driver on most lines [S1].
Material composition has a smaller effect than these four axes: the working element is a bimetal strip (typically a copper-clad Invar or manganese-copper alloy); auxiliary contacts are silver-alloy; the housing is glass-filled PA66 or equivalent thermoplastic. None of these materials are 2026 supply-constrained in the price band covered here, so spot movements in copper or silver move the OEM tier only marginally.
Selection criteria that should override lowest price
For motor-circuit protection the cheapest thermal relay on Made-in-China.com is rarely the right answer for industrial duty, and the Thermal Relay Buying Guide 2026: Spec Gates, Sourcing Tiers and Match Rules lays the gating logic in detail. A practical spec map for 2026 selection — pairing the TECO RHU/RHN spec sheet against typical motor circuit designators — is documented in Thermal Relay Selection Criteria: Motor Circuit Spec Map, and the boundaries between thermal relay and brake-resistor topologies are drawn in Thermal Relay vs Brake Resistor: Spec Boundaries and Sourcing Rules. Three non-negotiables should override unit price: [S1]
1. Trip-class match to motor starting duty. A class 10A relay (such as the TECO RHU/RHN [S1]) is correct for normal-start AC induction motors; a class 20 or 30 is required for high-inertia loads such as conveyors, mixers, or crushers. Under-classed relays nuisance-trip on start; over-classed relays let the motor cook during a stall.
2. Phase-failure protection. Verified on the TECO datasheet [S1]; commonly omitted on the cheapest US$2.00 tier [S2][S4]. For three-phase motors above 0.37 kW, phase-loss without detection destroys windings within seconds.
3. Certification stack matching the destination market. IEC + CE + RoHS for EU/Asia; UL + CSA for North America; GB for China domestic [S1]. A relay with only "CE — contact issuer for current status" [S5] is a documentation risk, not a price saving.
Comparison: entry-tier OEM vs mid-tier brand vs high-tier sealed
Side-by-side on four buyer-relevant axes, the 2026 catalog evidence [S1][S2][S4][S5] is unambiguous. On price-per-piece, the entry tier sits at US$2.00–3.00 (MOQ 100), the mid tier at 2–5x that for nameplate Lrd-pattern units, and the high tier at US$1,000/set (MOQ 5) [S4]. On current range, the entry tier usually publishes 0.5–25 A; the TECO RHU/RHN mid tier covers 0.1–38 A; the high tier typically starts at 40 A and runs to 200 A+ [S1]. On certifications, the entry tier lists CE with caveats; the mid tier adds IEC + GB + UL + CSA + RoHS per the TECO spec sheet [S1]; the high tier bundles IEC, GB, and full type-test reports.
On lead time and MOQ flexibility, the entry tier is the most negotiable and ships from stock in Zhejiang and Guangdong; the mid tier is sold through authorised distributors with fixed SKU pricing; the high tier requires a 5-set MOQ and is built to order against a specification. For a small-panel builder buying 50 units per quarter, the entry tier's US$2.00 line item is correct. For a 50-unit-per-day motor-control panel shop, the mid tier is the lowest total-cost option once nuisance-trip rates are priced in. For OEM machine builders exporting to EU and North America, the high tier's bundled documentation is the only passable answer.
Failure modes and limitations buyers should price in
Thermal relays fail in three primary modes, each of which is preventable at specification time. The first is contact welding on short-circuit: thermal relays are not short-circuit protection devices and must be paired with a fuse or circuit breaker sized per the relay's coordination type ("1" or "2" per IEC 60947-4-1). The second is bimetal drift under sustained ambient heat: in panels above 40 °C, the relay must be derated — TECO does not publish the derating curve on the catalog page, so buyers must request it [S1]. The third is phase-loss pass-through on single-phased supply: only relays with explicit phase-failure protection (TECO RHU/RHN has it [S1]) will trip; bare thermal units will simply heat both poles and let the motor burn out.
Limitations inherent to the technology are also worth pricing in. Thermal relays do not protect against instantaneous overcurrent (use a magnetic circuit breaker for that), do not protect against earth fault (use a residual-current device), and do not provide remote trip indication without an auxiliary contact block. The auxiliary contact block is the most commonly omitted item in a budget quote; verify it is in scope before signing a US$2.00 line item.
Sourcing playbook for 2026 procurement
The cost-of-acquisition data point on Made-in-China.com is honest: US$2.00 per piece is real for household-grade units [S2][S4], and US$1,000 per set is real for sealed industrial assemblies [S4]. The decision is whether your panel is a household appliance, a small commercial unit, or an industrial motor control center. For the first, the OEM tier with CE (status verified) and a 100-piece MOQ is fine. For the second, the Schneider-pattern Lrd line with full documentation [S5] is the standard answer. For the third, the TECO RHU/RHN bracket [S1] is the entry into the IEC + UL + CSA-certified mid tier.
None of these are predictions — they are the next observable nodes in the thermal relay cost stack.
For component-level specifications, see thermal relay, linear guide, and crossed roller guide.