We were able to connect six of them to a chain of three without any problems. A bulb stopped working after 7 months. We swapped the bulbs from one plug to another and found that after that short time we had a bad adapter (the 3 x 3 x 1 inch box that sits over the bulb). We are waiting for the manufacturer's response. to provide a replacement adapter. UPDATE: Interacted with Luminosum when one of the adapters failed - they sent a replacement free of charge within a few weeks. Good customer service!