SATCO Lighting S9543 1.6W, JC LED, 5000K, G4 Base, 12V AC/DC

That's exactly the swap it's built for. The S9543 is a bi-pin G4 lamp running on 12 volts AC or DC, drawing 1.6W at 0.133 amps, and Satco rates it as the equivalent of a 10W incandescent. It puts out 200 lumens. Because it accepts both AC and DC at 12V, it works on a magnetic or electronic 12V supply and on battery/DC landscape runs. The one thing to check is your transformer: a 1.6W load is a fraction of what the old halogen pulled, so a transformer with a high minimum load may not fire a single lamp on its own.

Yes. The S9543 is an enclosed rated lamp, so a sealed or gasketed fixture where heat builds up is a legitimate application. It also carries a damp location rating, which covers covered porches, soffits, bath areas and similar spots with moisture in the air, but not direct water exposure or submerged/in-ground use. Burning position is universal, so base up, base down or horizontal are all fine.

Order Satco S9543. It is a 1.6W JC style LED with a bi-pin G4 base on a silicon body, 5000K, clear, 12V AC/DC. G4 is the 4mm pin spacing bi-pin, not the 6.35mm GY6.35 used on many 20W and 35W halogen capsules, so confirm which one your fixture takes before ordering. The lamp ships in a single clear version, with no finish or color temperature options to specify.

Only where it stays out of the weather. The rating is damp location, which covers a shielded, covered outdoor position such as a soffit or a sealed fixture under an eave. Direct rain, sprinkler spray or an in-ground well light needs a wet location rated lamp instead. Inside a suitable sealed housing the enclosed rating means heat buildup is not a problem.

The lamp itself is dimmable. On a 12V system the dimming happens ahead of the lamp, at the transformer or driver, so the result depends on that supply being a dimmable low voltage type and matched to your dimmer (magnetic vs electronic). At 1.6W the load is small enough that one or two lamps on a channel may sit below the dimmer's minimum load and flicker or drop out at the bottom of the range.

Output is 360 degrees around the lamp, so it throws light all the way around rather than in a beam. That matches how a JC halogen capsule behaves in a reflector fixture or a diffused cabinet light. The T3 tubular body has a clear lens, so in an open fixture the diodes are visible and the light is a little sharper than a frosted lamp would give.

The case is the labor, not the lamp. Rated life is 25,000 hours against roughly 2,000 for a typical halogen G4, and each fixture drops from about 10W to 1.6W. On accent and cabinet runs burning 12 hours a day, that is years between ladder trips instead of months. For a property manager standardizing a fleet, note the 5000K color: fix on one temperature across the building or the relamped fixtures will read cold next to the ones still on halogen.

It is Title 24 compliant, which matters on California residential permits where high efficacy lamps are required in specified locations. It is also FCC compliant for electromagnetic interference. It does not carry DLC listing, so it will not qualify for utility rebate programs that require a DLC listed product.