I use something like this at the end of the wire and run to the terminals underneath the track. Please note I'm not 100% on the size, you may want to Google and see the right size for fast track:

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https://smile.amazon.com/Baomain-disconnects-Insulated-Connector-Electrical/dp/B01G51ELT8/ref=sr_1_9?dchild=1&keywords=electric+spade+connectors&qid=1617558048&sr=8-9