That photo helps a lot - it is already factory wired for a single-phase connection such as we have here in the US.
tedcohen wrote:OK, so, I will buy a three-prong PLUG for the THREE-WIRE armored cable coming from the back of the stove. (No need for a so-called range cord since the range has its own armored cable that simply needs a plug.)
Correct.
Why the instructions say range "must be wired with a three-phase, FOUR-PRONG cord" escapes me - since the armored cable coming from the rear of the stove is a THREE-WIRE cable.
They probably printed up one set of installation instructions and then tried to adapt it to different wiring systems.
A tag on that armored cable says, "Frame grounded by connection of grounding lead to neutral lead. If local codes do not permit grounding through neutral, open the connection and use grounding lead to ground unit. Connect neutral lead to branch-circuit neutral conductor in usual manner."
A second tag says, "No need to use neutral. The potential at the power supply electrical connections shall be 150 volts to ground or less."
Yes, that does mess with the mind as that is not what is shown in Figure 24 of the installation instructions and the two statements contradict each other to an extent (no neutral is 'needed' because there are apparently no 120 volt loads, which means all the light bulbs (lamps) will be 240 volt, as will all the controls, fan motors (if any), etc - so a neutral is not "needed" for anything, however, the neutral connection within the range is apparently bonded (connected) to ground, which means that they could (should not, but 'could') be using the neutral-bonded-to-ground-as-a-neutral-connection for 120 volt lamps. If your lamps are 120 volts, then the neutral SHOULD NOT be connected to ground, and that would mean re-wiring the circuit to a four-wire circuit ... except that your house was built in 1961 when a three-wire circuit was allowed, and the neutral current was permitted to be on the ground conductor - not the safest wiring, but what was allowed 'back then' and one more reason it is no longer allowed.
Be that as it may be, the photo shows a 'factory supplied' 'pig tail' with 'red' (hot), 'black' (hot), and a 'green' (ground) conductors to be connected to the circuit. HOPEFULLY ... all factory wiring beyond what is shown in the photo is correctly done. If so, your dual-fuel range is wired for connection to a 240 volt ONLY circuit, with a ground for the metal case of the range.
So, I assume that since I am using a three-wire receptacle since my house is pre-1996 that I should leave the armored cable connection as it came from the manufacturer and not open it up and split the ground and the neutral?
Options:
1) IF ... you do not already have a three-wire (three-slot) receptacle installed, make the pigtail connection directly into the electrical box with the appropriate cover which has a connector to receive that pigtail.
2) IF ... you have a three-wire (three-slot) receptacle installed, then remove that pigtail and replace it with a three-wire range cord which has a three-prong plug on it.
Options 1) and 2) are the proper ways to connect that range as that pigtail is not intended or designed to have a plug installed on the end of it.
You need a disconnect for that range, a cord and plug into a receptacle serves as that disconnect; if you directly wire that pigtail into the electrical box, then a disconnect is needed either there or at the panel, I will presume that your 1961 house has breakers, and if it does, then get a 'breaker lock out' device (available for different many types of panels, but may no longer be available for some older discontinued panels). A breaker lock out device fits over the breaker behind the panel cover (so it stays in place at all times) and when the breaker is flipped 'off', a small lock can be installed so you can safely work on the wiring without anyone turning the breaker 'on' while you are working on it ... no need to cook you while trying to hook up the range to cook dinner ... not a good thing to do.
The above may sound like a silly additional precaution to you (or others), but it is neither a silly nor a little precaution if you ask the
surviving spouses of those who thought it was a silly little thing to do.