Short answer. Not necessarily. Although delivery to a carrier is normally treated as delivery to you, Article 1523 makes an exception when the seller fails to make a reasonable carriage contract. If he omits that and the goods are lost in transit, you may decline to treat delivery to the carrier as delivery to yourself, or hold him responsible in damages.
What the law says
Unless otherwise authorized by the buyer, the seller must make such contract with the carrier on behalf of the buyer as may be reasonable, having regard to the nature of the goods and the other circumstances of the case.
Civil Code, Article 1523 — Delivery to the Carrier Is Delivery to the Buyer. Read the full provision →
What the law says
If the seller omit so to do, and the goods are lost or damaged in course of transit, the buyer may decline to treat the delivery to the carrier as a delivery to himself, or may hold the seller responsible in damages.
Civil Code, Article 1523 — Delivery to the Carrier Is Delivery to the Buyer. Read the full provision →
The general rule: carrier delivery counts as delivery to you
Where a seller is authorized or required to send goods to the buyer, Article 1523 lays down a default: delivery of the goods to a carrier, whether named by the buyer or not, for the purpose of transmission to the buyer is deemed to be a delivery of the goods to the buyer. In a shipment sale, then, handing the goods to the carrier ordinarily transfers the risk to you — which is why a loss in transit is usually the buyer's problem. But this default carries conditions, and your situation falls into one of the exceptions that shifts the risk back onto the seller.
The seller's duty to arrange carriage reasonably
The default assumes the seller did his part properly. The article imposes a specific duty: Unless otherwise authorized by the buyer, the seller must make such contract with the carrier on behalf of the buyer as may be reasonable, having regard to the nature of the goods and the other circumstances of the case. In plain terms, the seller must arrange carriage sensibly — choosing terms and a mode of transport suited to what is being shipped. Fragile, perishable, or valuable goods call for more care. Simply dumping the goods with any carrier on any terms is not enough to pass the risk to you.
What you can do when he fails
Here is the part that answers your question. The article continues: If the seller omit so to do, and the goods are lost or damaged in course of transit, the buyer may decline to treat the delivery to the carrier as a delivery to himself, or may hold the seller responsible in damages. You have two routes. You may refuse to accept that handing the goods to the carrier counted as delivery to you — so the loss stays with the seller, as if he never delivered. Or you may treat it as delivery but sue the seller for the damages his careless arrangement caused you.
A related trap: notice to insure
The same article guards against one more failure. Where goods are sent under circumstances in which the seller knows or ought to know that it is usual to insure, he must give you notice that lets you insure them during transit; if he fails, the goods shall be deemed to be at his risk during such transit. So even apart from a poor carriage contract, a seller who leaves you unable to insure carries the risk himself. What none of this does is make the seller an absolute insurer in every shipment — the risk shifts back to him because of a specific omission on his part, not automatically whenever goods happen to be lost.