Is a ten guage solid copper wire safe to use for a range?

What is the amp requirement for the range? If it is 30A or less, the #10 wire is fine. If it is 40A, the #10 is too small. And what size breaker is at the other end of those #10 wires? If it is 30A, again OK, 40A and it has been dangerous all along.

For a safe and code compliant setup, everything has to be compatible:

• the breaker
• the wire
• the receptacle
• the range cord / plug
• the range itself

What you can use is determined by the range; the manufacturer's instructions will state what operating voltage and ampacity is suitable for the electrical circuit.

The breaker is the main safety device, it protects the wire from starting a fire if there's a short or overload. If you have 10 gauge wire, you're probably limited to a 30 amp breaker. Most ranges require a 40 amp or 50 amp breaker.

The receptacle has to be suitable for the ampacity of the circuit. The NEMA specifies a receptacle configuration for all the various circuits / ampacities. Ranges usually operate on combination 240/120 volt circuits, and either 40 or 50 amps. Many will also run on 208/120V circuits, and some will only operate on 208/120V circuits.

The range is usually sold with the NEMA cord and plug for the NEMA receptacle that's suitable for the type of circuit your range requires, if it is not included with the range, the appliance store will usually sell one that's suitable per the manufacturer's instructions. They may sell you both a three prong and four prong cord and plug set for your range; older homes often have three prong circuits with no safety ground, and have three wire receptacles. Newer work will have four wire 120/240V range circuits with four wires circuits and four slot receptacles. You would (carefully) follow the manufacturers instructions to attach the three-wire or four-wire cord to terminals in the range.

Unless your range is made for a 30 amp circuit, you're probably going to have to run new wire. Even if your range operates at 40A, I'd install a 40A breaker and receptacle with wire capable of 50A. There's nothing wrong with oversizing the wire, and this way you can upgrade the stove by changing the breaker and receptacle without changing the wire.