A 14 year old is pretty mature at least most of the 14 year olds I've known are pretty mature so you can usually leave a 14 year old alone at home for around 5 hours or longer and sometimes overnight.
Just make sure you can trust the 14 year old to be unsupervised for the length of time and let them know who to contact in an emergency.
Also it would be a good idea to have a trusted neighbor come over and check on them if possible although the 14 year old may not like that.
But sometimes you need too.
Also check with your local state laws because some states have laws in place that state when a child can be left alone at a certain age.
And if someone were to turn you in then the child could be taken away from you and then you could face child endangerment charges.
But most 14 years can stay home alone safely for at least 5 hours if not longer.