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Prices and specs checked 20 September 2026 · not a hands-on test · not a wiring diagram
Inlet box and generator interlock: the middle path between cords and an automatic panel
Cords are enough for fridge, CPAP, and a router. Automatic panels are a different SKU. Between them sits a listed generator inlet plus a panel interlock (or a small manual transfer switch) — selected house circuits, flipped by hand, installed by a licensed electrician.
Edited by K Singh. contact@outageshield.com. Manufacturer pages and dated list prices only. No invented homeowner stories. No test lab. No backfeeding.
This page deep-dives the inlet / interlock path. The hub overview — cords, brand transfer kits, inlet/interlock, and Smart Home Panel 3 — stays on how to connect a portable. Soft-start well-pump detail is queued for a later Sunday; surge honesty for wells is on the well pump guide. For duration math on a longer outage, use generator vs battery vs hybrid.
1. Who this is for
You already own (or will buy) a cart-ready portable with honest 120/240 V capacity — typically Anker SOLIX F3800-class, EcoFlow Ultra X path, or a BLUETTI EP900-class stack — or a portable generator with a proper outlet. You want selected house circuits without running cords through the kitchen every outage. You will hire a licensed electrician and pull a permit where the AHJ requires one.
You are not shopping for automatic whole-home transfer yet (EcoFlow Smart Home Panel 3 with Ultra X, installer Powerwall / OCEAN Pro, or ATS + standby generator). If your keep list is three plugs, stay on cords — that is a real backup.
2. Three paths compared
| Path | What you get | Typical cost shape | When it fits |
|---|---|---|---|
| Extension cords / temporary | Individual loads at the battery or generator | Cord + discipline | Fridge, CPAP, router, lamps. No panel work. |
| Inlet + interlock (this page) | Selected breakers fed from a listed inlet; mechanical interlock so utility and backup cannot both feed the panel | Inlet + cord + interlock kit + electrician labor | Multi-circuit backup you flip by hand when the grid dies |
| Automatic transfer / brand panel | Near-seamless or automatic transfer of many circuits | SHP3 $3,099 (20 Sep 2026) with Ultra X; Anker transfer / HPP on F3800 family; installer systems | High circuit count or automatic transfer; accept SKU + install |
Brand kit note: EcoFlow’s portable transfer switch kit lists at $399 (20 Sep 2026) for a Reliance-style 6-circuit switch aimed at DELTA Pro 3 / DELTA 3 Ultra Series — electrician install, indoor panels, not Smart Home Panel 3. Anker documents transfer / inlet / Home Power Panel on the F3800 Plus page. A panel interlock is panel-specific hardware that must match your enclosure — not a photo.
Shop-ready sources first. Confirm checkout prices — they move.
View F3800 on Anker View Ultra X on EcoFlow View transfer kit on EcoFlow3. What an inlet box does (and does not)
A generator inlet box is a weather-rated outdoor (or garage) receptacle that accepts a matching male plug from your generator or from a portable power station’s 120/240 V outlet via a properly rated cord. The inlet feeds conductors that land on a breaker or transfer device — not into a dryer receptacle with a suicide cord.
It does: give you one listed place to plug in; keep the cord out of living space; make a repeatable outage routine (plug in → flip interlock → select breakers).
It does not: allow the whole panel to stay energized while the utility is still connected; size your battery for you; turn a 120 V-only pack into a 240 V well-pump solution.
Match voltage, amperage, pole count, and connector type (commonly 30 A L14-30-class for many portables; some systems use 50 A). Match cord gauge to ampacity.
4. What a generator interlock kit does (and does not)
A panel interlock kit is a mechanical slide or bracket that prevents the main utility breaker and the backup/generator breaker from being ON at the same time. When installed correctly on a compatible panel, it is how many jurisdictions allow selected-circuit backup without a full automatic transfer switch.
It does: enforce break-before-make between utility and backup; let you feed a subset of branch breakers from the inlet when the main is OFF and the backup breaker is ON.
It does not: substitute for a listed transfer switch in every jurisdiction; protect against every miswire; turn an undersized portable into whole-home air conditioning.
The interlock exists so your backup cannot push voltage onto the utility lines while the main is closed. Treat it as a life-safety device, not a convenience gadget. Never backfeed through a wall receptacle.
5. Code, permit, and honesty rules
- Hire a licensed electrician. Panel covers, bonding, and enclosure listings are not DIY YouTube work for most homeowners.
- Permit and AHJ. Many cities require a permit. Local amendments beat generic advice. Interlocks are not accepted everywhere as a transfer-switch substitute.
- Utility rules. Some utilities have disconnect or interconnection requirements even for temporary backup.
- No backfeeding. Never plug a generator or power station into a wall receptacle to “power the house.”
- Well pumps and 240 V surge. An inlet can reach a 240 V breaker; it does not guarantee your portable can start the motor. See well pump backup. Soft-start detail is a later Sunday — not this page.
We will not publish a wiring diagram for your specific panel. Panel type, bonding, and local code vary. Product links are categories and brand kits, not a promise they fit your enclosure.
6. Must-run loads first — then pick the path
Write the circuits you will keep before you buy an inlet. Gate order on OutageShield: must-run loads → 240 V / surge honesty → outage length (kWh) → cords vs inlet/interlock vs automatic panel.
| Load | Why it shows up on an inlet job |
|---|---|
| Refrigerator / freezer circuit | High value; modest average watts; often the first kept breaker |
| Furnace control / blower (gas) | Pipe-freeze risk; not a heat-pump compressor |
| Sump pump | Start surge each cycle; usually 120 V |
| Well pump (if present) | Often 240 V + LRA gate — fails closed on surge before Wh |
| Lighting / receptacle for medical / phones | Or stay on cords if simpler |
Full matching table on the hub: how to connect a portable. Cold 2-day worksheet: ice-storm 2-day backup. Tick boxes on the checklist.
7. When battery + inlet makes sense vs generator-only
Inlet + interlock fits when you want selected circuits without dragging cords every storm, you can operate a manual flip under stress, and your portable or generator has a matching outlet plus honest surge headroom.
Prefer cords when the keep list is three plugs or panel work is blocked (rentals).
Prefer automatic / brand panel when you want many circuits or near-seamless transfer. EcoFlow Ultra X + Smart Home Panel 3 is the cart-ready EcoFlow automatic path (starter $7,999 / with SHP3 $10,999; SHP3 alone $3,099 — us.ecoflow.com, 20 Sep 2026). SHP3 does not talk to DELTA Pro 3. Installer systems are a different buying process — OCEAN Pro vs Powerwall 3.
The same inlet/interlock hardware often serves a portable generator later. Hybrid thinking (quiet battery nights, generator recharge) is on generator vs battery vs hybrid.
8. Shop-ready kit pointers (20 September 2026)
| Kit / unit | Role with inlet path | Price snapshot |
|---|---|---|
| Anker SOLIX F3800 | 120/240 V portable candidate for selected circuits via inlet/transfer | $2,199.99 list (Anker SOLIX US) — do not restore $1,999.99 promo |
| EcoFlow DELTA Pro Ultra X | Whole-home-capable stack; SHP3 for automatic path | $7,999 starter; Ultra extra rail $2,299 on Ultra X PDP |
| EcoFlow Smart Home Panel 3 | Automatic 32-circuit path — not a generic interlock | $3,099; Ultra X + SHP3 $10,999 |
| EcoFlow transfer kit | Brand 6-circuit manual transfer for certain DELTA portables | $399 |
| BLUETTI EP900 + B500 | Higher continuous kW stack; panel path is AHJ/installer territory | List (search cards, 20 Sep 2026; all Out of stock): EP900 + 2×B500 + sub panel $10,298 · + 3×B500 + sub panel $13,798 · + 4×B500 + sub panel $17,298. Cart/buy-box not live (PDP 404 / OOS) — confirm live cart before buy. Not dual-inverter kits. |
| Generic 30 A inlet + panel-specific interlock + cord | The literal subject of this article | Varies — match your panel label |
Path/list on Anker SOLIX US, 20 Sep 2026. Promo kill — not $1,999.99.
View F3800 on Ankerus.ecoflow.com only. Extra rail $2,299 on Ultra X PDP. No invented CJ hop.
View Ultra X on EcoFlowSearch-card list 20 Sep 2026: EP900 + 2×B500 + sub panel $10,298 · + 3×B500 + sub panel $13,798 · + 4×B500 + sub panel $17,298. All OOS; cart/buy-box not live — confirm live cart before buy. CJ evergreen 15736238.
View EP900 kits on BluettiPanel-specific. Search; do not assume one SKU fits.
View inlets on AmazonMore tables: shop-ready portables, 2026 rankings, Find my backup, SHP3 notes.
9. Practical sequence (still not a wiring diagram)
- Write must-run circuits and nameplate watts / LRA where relevant.
- Confirm the portable or generator outlet type and continuous/surge ratings.
- Ask the electrician which listed method your panel and AHJ allow (interlock vs transfer switch vs brand panel).
- Buy the matching inlet, cord, and kit — after the electrician names the panel type.
- Install under permit; label the interlock procedure at the panel.
- Test on a calm afternoon: flip, walk every kept circuit, write what you forgot on the checklist.
FAQ
Is an interlock the same as a transfer switch?
No. An interlock is usually a mechanical kit on your existing main panel. A transfer switch is a separate listed device that moves loads between utility and backup. Some AHJs accept one and not the other.
Can I use an inlet with a portable power station?
Yes, if outlet, cord, and inlet ratings match and the station can supply the kept loads. Many homeowners use the same inlet for a generator later. Follow the manufacturer’s house-connection guidance. Never backfeed a wall receptacle.
Do I need Smart Home Panel 3 for an inlet?
No. SHP3 is EcoFlow’s automatic panel for Ultra X. Inlet + interlock is a different, usually lower-cost manual path.
Will this run my whole house?
Only if you size the source and keep an honest breaker list. Most inlet/interlock jobs are selected circuits, not every breaker left on.
Can this start my well pump?
Maybe. 240 V and locked-rotor amps fail closed before Wh. No guarantee on this page. See the well pump guide.
Sources (checked 20 September 2026)
- EcoFlow US: Ultra X, Ultra extra battery, Smart Home Panel 3, transfer switch PDPs (us.ecoflow.com)
- Anker SOLIX F3800 PDP (ankersolix.com/products/f3800) — path/list $2,199.99
- BLUETTI EP900 search cards / landing (bluettipower.com/pages/ep900b500) — list snapshots 20 Sep 2026 ($10,298 / $13,798 / $17,298 for 2/3/4×B500 + sub panel); all Out of stock; cart/buy-box not live — confirm live cart before buy
- OutageShield hub: how-to-connect-portable-home-backup.html (must-run loads polish)
Next step: write the must-run list, then choose cords vs inlet/interlock vs automatic panel.
Connect hub Find my backup Shop-ready Generator vs battery ChecklistEditor: K Singh. Sources/prices checked 20 September 2026. Page dated 20 September 2026. Not a hands-on test. Not electrical or tax advice for your jurisdiction. We do not guarantee well-pump starts.