Hi,

I have a new Dimplex EMC-4240 240V, 4,800 watt, 30 amp portable garage heater with a NEMA 6-30 (3 prong) plug at the end of a 6' cord. However the receptacle in my garage is a 2 phase, 3 pole, 14-50 receptacle, formerly used for a garage oven. The instructions advise against use of adaptors or extension cords so to use the heater safely I must replace the existing 14-50 receptacle with a one phase, 2 pole, 6-30 receptacle.

My thought as to how to do this is: 1) switch off power to the receptacle at the main breaker panel and test to ensure all conductors are dead, 2) disconnect the existing 14-50 receptacle, 3) connect the bare/green wire to the ground connection on the 6-30 receptacle and the hot black and red wires to the other two connections, and terminate the unused neutral white wire with a marette, inside the box.

Would this be the correct approach?

Do I also need to change the current 40 amp breaker switch for a 30 amp breaker switch?

Any informed advice would be much appreciated.

There isn't a "2 phase" electrical service. There are three(sometimes four) wires. One pole is 120, the other is 120 , a neutral and now an equipment ground.
The "unused white neutral" should be connected to the same terminal as the ground (green). The breaker needs to be reduced to 30 amps. If you are not sure how to do this, to err on the side of caution, pay an electrician to do it for you. I have done a lot of electrical work in the last 40 years,, it's only friendly if you KNOW WHAT YOU ARE DOING!! Good Luck.

Never refer to a breaker as a "switch". They are not designed to be used as switches.

There isn't a "2 phase" electrical service. There are three(sometimes four) wires. One pole is 120, the other is 120 , a neutral and now an equipment ground.
The "unused white neutral" should be connected to the same terminal as the ground (green). The breaker needs to be reduced to 30 amps. If you are not sure how to do this, to err on the side of caution, pay an electrician to do it for you. I have done a lot of electrical work in the last 40 years,,,,,it's only friendly if you KNOW WHAT YOU ARE DOING!!! Good Luck.

Never refer to a breaker as a "switch". They are not designed to be used as switches.

Thanks for the answer. I stand corrected; what I meant was that the existing receptacle is wired to provide both 120V and 240V supply (for the former oven). My reference to 2 phase was wrong. I have two hot 120V wires, a neutral and a ground.

(I will also stop referring to breakers as switches! I do use them only for the purpose they are intended but thanks again for the advice.)

That's OK Guy... just glad you walked away knowing and understanding a little bit more. THat is the great thing about life,, we can always learn something new! Good Luck