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Written from the listing's specs, not from our own use · How we rate
On paper, the Marsflex 30A L14-30P Inlet Box gets the important things right: a 30 amp inlet (L14-30P) and a weatherproof cover. Think of it for a proper hookup to the house panel: 7.2/10 on what its listing documents.
| Brand | Marsflex |
|---|---|
| Category | Covers, cords & accessories |
| Amp rating | 30 A |
| Plugs and connectors | L14-30P, L14-30R |
| ASIN | B0CZ8RPH88 |
Full listing title: Marsflex 30 Amp Generator Power Inlet Box, L14-30P, Weatherproof Outdoor
Rated from the listing's specs, no buyer reviews yet
What it's made for: a proper hookup to the house panel.
Two power inlet boxes with the same amp rating, closest to it on our rating, each with a dated price.
The rating the listing states. It has to match the cord and the biggest outlet on your generator: a 30 amp inlet won't pass a 50 amp generator's full output.
What it has going for it
30 A inlet, L14-30P. The weatherproof socket on the outside wall where the generator cord plugs in. An electrician wires it to a transfer switch or an interlock, and you never backfeed through a dryer outlet.
Weatherproof box. It lives on the outside wall all year, so the cover and its rating (NEMA 3R where stated) matter.
The Marsflex 30A L14-30P Inlet Box is the socket on the outside wall, rated 30 A with a L14-30P inlet, per the listing. Indoors it feeds either an interlock kit on the main panel or a manual transfer switch.
An interlock is cheaper and leaves every breaker available; you manage the load yourself. A transfer switch puts a set list of circuits on the generator, which is simpler on the night. Either way, a licensed electrician wires it.
The seller states, word for word, in the Marsflex 30A L14-30P Inlet Box listing:
It's rated for 125/250V, 7500W, and 30 Amps.
Marsflex 30Amp Generator Power Inlet Box features sturdy and durable design and is certified with an excellent NEMA 3R protection level.
The seller's words, quoted as written; we haven't measured them. Your generator's manual decides whether it fits.
What the Marsflex 30A L14-30P Inlet Box listing names:
Check these figures against your generator's manual before you order.
On Sep 30, 2026, that price put it in the cheaper third of the 11 power inlet boxes we have a recent price for.
Count the electrician and, where your town asks for one, the permit on top: the hardware is the cheap part.
The button opens the exact listing (ASIN B0CZ8RPH88), where today's price, stock and seller apply.
Running a 50 amp generator? The SURAIELEC 50A Inlet Box (7.4/10) is rated 50 A.
Our take
The Marsflex 30A L14-30P Inlet Box earns its place with a 30 amp inlet (L14-30P) and a weatherproof cover. No buyer reviews yet, so this Marsflex power inlet box has to win you over on paper. Our main reservation: one wrong plug code and nothing connects, so check both ends first. We'd pick it if you want a clean, legal hookup to the panel; otherwise, put it next to the RVMATE 50A SS2-50P Inlet Box first.
Before the Marsflex 30A L14-30P Inlet Box goes in your cart, check the plug code: it takes L14-30P, and the cord and the generator outlet have to match.
This one uses L14-30P and L14-30R. Read the outlet code on your generator panel and the inlet box (L14-30, L5-30, 14-50, SS2-50, TT-30); they are not interchangeable.
An inlet box connects to a transfer switch or an interlock, wired by a licensed electrician. Our interlock vs transfer switch guide compares both.
It is rated 30 A. The cord, the inlet and the switch should all carry the same rating as the generator outlet you use.
How the Marsflex 30A L14-30P Inlet Box stacks up against the closest alternative, the RVMATE 50A SS2-50P Inlet Box.
| Criterion | Marsflex 30A L14-30P Inlet Box | RVMATE 50A SS2-50P Inlet Box |
|---|---|---|
| Our rating | 7.2/10 | 7.3/10 |
| Rating | 30 A | 50 A |
| Plug | L14-30P | SS2-50P |
Pick the RVMATE 50A SS2-50P Inlet Box if you want our higher-rated option (7.3/10).
We rate it 7.2/10 (good). The rating comes from its documented listing alone, as no customer-review record is captured yet.
Only if your generator manual confirms it. Check the outlet or plug type, the amperage, the list of supported models and any adapter the manual asks for; looking similar is no proof that it fits.
Its listing states a 30 amp inlet (L14-30P) and a weatherproof cover. These are the seller's figures, not our measurements: whether it fits your exact generator is worth confirming first.
Match the plugs: this one uses L14-30P and L14-30R. Read the outlet code on your generator panel and the inlet box (L14-30, L5-30, 14-50, SS2-50, TT-30); they are not interchangeable. Plan the install: an inlet box connects to a transfer switch or an interlock, wired by a licensed electrician. Our interlock vs transfer switch guide compares both. The amp rating: it is rated 30 A. The cord, the inlet and the switch should all carry the same rating as the generator outlet you use.
We link to the exact listing on Amazon, where today's price, stock and seller apply. It is an affiliate link, and it has no effect on the rating.
No, we haven't used it ourselves. Everything on this page comes from its listing, read line by line and weighed with our published formula, plus our editors' read of how it compares with its rivals.