Hi Daley,
I noticed that you referred to the receptacle as "non-standard." That is a standard, but infrequently used NEMA 6-15 receptacle designed for 15 A in our 220-240V system. Even Home Depot has them. Since most appliances that require the higher voltage in the US, e.g., electric ranges and heaters, also require higher current, it is not often used. Small tools, e.g., table saws, don't require such high current, and that is where you will often see it used. Since it is infrequently used and is not compatible with any of the common 115 V connectors, it is also used for low-voltage DC connections, as in campers and such. I don't think code applies to such use, but it prevents accidentally plugging such things into a typical 115V receptable. Here is the link to Cooper that shows one: **broken link removed**
Back OT, I think the safest step is to photograph and try to draw what you have as a record. I would then remove all of the black wires and rewire from scratch using the common US color code and the datasheet posted above. Just as a reminder, our code is: Color (often black or red) = L (line), White = common ("grounded" wire) and Green = ground wire. Note the distinction between "grounded" and "ground".
Since Variac's are very expensive new, you may want to make a test supply cord so you don't smoke it. Yes, the wiper is fused. If you have a small regular light bulb, say 25W to 60W bulb, wire it in series in the black wire of your supply cord. Then if you have a short, you will limit the current by the bulb (i.e.,25W at 120V is only 0.2A).
John
I noticed that you referred to the receptacle as "non-standard." That is a standard, but infrequently used NEMA 6-15 receptacle designed for 15 A in our 220-240V system. Even Home Depot has them. Since most appliances that require the higher voltage in the US, e.g., electric ranges and heaters, also require higher current, it is not often used. Small tools, e.g., table saws, don't require such high current, and that is where you will often see it used. Since it is infrequently used and is not compatible with any of the common 115 V connectors, it is also used for low-voltage DC connections, as in campers and such. I don't think code applies to such use, but it prevents accidentally plugging such things into a typical 115V receptable. Here is the link to Cooper that shows one: **broken link removed**
Back OT, I think the safest step is to photograph and try to draw what you have as a record. I would then remove all of the black wires and rewire from scratch using the common US color code and the datasheet posted above. Just as a reminder, our code is: Color (often black or red) = L (line), White = common ("grounded" wire) and Green = ground wire. Note the distinction between "grounded" and "ground".
Since Variac's are very expensive new, you may want to make a test supply cord so you don't smoke it. Yes, the wiper is fused. If you have a small regular light bulb, say 25W to 60W bulb, wire it in series in the black wire of your supply cord. Then if you have a short, you will limit the current by the bulb (i.e.,25W at 120V is only 0.2A).
John