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Electrical Installation Guide - Harvia Vega CompactUpdated 2 months ago

Electrical installation guide

Harvia Vega Compact (HCBU352401, 3.5 kW / 240 V / 1-phase) with low-voltage lighting & fan. Recommended method: a single 240 V circuit, split at an exterior junction box.

This guide is written for a licensed electrician and states the recommended wiring approach and the non-negotiable requirements. Means and methods are left to the electrician's judgment and experience, consistent with the NEC, local code, and the current Harvia manual. Confirm all ampacities and conductor sizes for the specific installation.

Downloads

Download the wiring guide (PDF). Hand this to your electrician — it includes the one-line diagram and the J-box splice detail.

Download the Harvia heater manual (PDF). Manufacturer's owner's/operator's manual for the HCBU352401.

Circuit summary

  • Source: One dedicated 20 A two-pole (240 V) breaker. No GFCI / GFI / RCD.
  • Home-run conductors: #12 AWG copper minimum (20 A, NEC 240.4(D)); 90 °C (194 °F) rated inside sauna walls.
  • Split point: Junction box mounted on the exterior of the sauna wall; conductors spliced with listed connectors.
  • Heater: Harvia HCBU352401, 3.5 kW, 14.4 A — 2 conductors + EGC to terminals 1, 2, ground.
  • Low-voltage supply: Mean Well LRS-50-12 (100–240 V in, 12 V out) feeding LED lighting + fan — 2 conductors + EGC.
  • Total load: ~15 A (heater 14.4 A + LV supply under 0.5 A); within the 16 A continuous limit.

System overview

The heater and the low-voltage lighting/fan supply share a single 240 V branch circuit. The circuit is split at a junction box on the outside face of the sauna wall, so the splice and connectors stay out of the heated, humid interior. Only the final runs to the heater and to the LV supply cross into the room.

System one-lineOUTSIDEINSIDE — sauna hot roomPANEL20 A · 2-pole (240 V)NO GFCIEXTERIORJ-BOXsplice / split2 hots + EGC#12 CuSAUNA HEATERHCBU352401 · 3.5 kWheater: 2 + EGCLV SUPPLYLRS-50-12100–240 V → 12 VAC: 2 + EGCLED + FAN12 V DCConductors entering the hot room: 90 °C copper in seal-tight conduit · no plugs or receptacles inside the sauna
Figure 1. System one-line. One breaker feeds an exterior J-box, which splits to the heater and the low-voltage supply.

Recommended method — exterior J-box split

Run the branch circuit as a single home run to an exterior junction box, then split to the two loads:

  • Source: one 20 A two-pole (240 V) breaker, dedicated to this circuit. Do not use a GFCI/GFI/RCD breaker — the heater elements nuisance-trip it and it voids the heater warranty.
  • Home run: two hots plus an equipment ground, #12 AWG copper minimum, to a junction box on the exterior of the sauna wall (a listed PVC or metallic box; keep the box and splice out of the hot room).
  • Split: in the J-box, splice each conductor 1-in / 2-out with listed connectors — one set to the heater, one set to the LV supply. Mind box fill (NEC 314.16). Do not double-lug the breaker.
  • Heater feed: 2 conductors + EGC via seal-tight flexible conduit to the heater junction box; land Line 1 → 1, Line 2 → 2, ground → lug. Provide a fixed all-pole disconnecting means.
  • LV-supply feed: 2 conductors + EGC to the supply's 100–240 V input (L / N / ground on the LRS-50-12). The 12 V DC output runs to the LED lighting and fan.
  • Inside the room: any conductors entering the sauna are 90 °C copper in seal-tight conduit, routed away from direct heat. No plugs, cords, or receptacles inside the sauna.
J-box splice detailJ-BOX SPLICE DETAIL — each conductor spliced 1-in / 2-outFROM BREAKERTWO OUTGOING SETSL1 (hot)→ to heater→ to LV supplyL2 (hot)→ to heater→ to LV supplyEGC (ground)→ to heater→ to LV supplyListed twist-on / push-in connectors · box fill per NEC 314.16 · bond all metallic parts · do not land two conductors under one breaker lug
Figure 2. J-box splice detail. Each conductor of the home run is spliced to two outgoing sets (heater + LV supply).

Critical requirements (do not deviate)

WARNING — No GFCI / GFI / RCD on this circuit (manufacturer requirement). If the AHJ requires GFCI on the lighting/fan specifically, isolate those loads on a separate GFCI-protected source — never place the heater on GFCI.

WARNING — Confirm the heater is permitted on a shared (non-individual) branch circuit under the current Harvia manual and local code. If an individual branch circuit is required, feed the LV supply from a separate circuit (or an existing outlet) instead of splitting this one.

NOTE — LV-supply siting is thermal, not just electrical. The LRS-50-12 and the LED controller have maximum ambient ratings. If the supply enclosure sits inside the room, verify the in-enclosure temperature during a worst-case session stays within the lowest-rated component's limit, with margin (a sealed box runs hotter than room air). Mounting the supply outside the wall and running only 12 V DC inward removes this concern entirely.

Commissioning

  • Verify terminations are torqued; heater and connecting conductors are copper; grounding is continuous.
  • Fill the heater with genuine sauna stones covering the elements; reset the overheat protector before first use.
  • Energize; confirm the heater heats and the lights/fan operate independently of the heater's timer/thermostat.
  • Label the breaker “SAUNA”; post the supplied CAUTION / WARNING signs per the manual.

Alternatives (if the J-box split is not suitable)

  • Existing 120 V outlet: keep the heater on its own dedicated 240 V circuit and power the LV supply (100–240 V input) from an existing 120 V circuit outside the sauna. No second breaker; supply and any plug stay out of the hot room.
  • Two breakers: heater on 20 A / 240 V; LV supply on its own breaker. Required if the heater must be on an individual branch circuit, or if independent GFCI on the aux loads is mandated.

Need more help?

Reference: Harvia Vega Compact / HCBU Owner's & Operator's Manual (16022023 / Y05-0583). This document supplements, and does not replace, the manufacturer's manual, the NEC, or local code.

If your electrician has questions, email [email protected] with your order number and we will help from there.

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