really? .89c ground lifters?

Jea48 - how can I tell whether my equipment is a three wire cord and plug deal or the kind that's safe?

...how can I tell whether my equipment is a three wire cord and plug deal or the kind that's safe?
04-24-10: Auxetophone

Auxetophone,

In the case of a three wire cord and plug if the equipment ground is not lifted and the electrical continuity integrity of the branch circuit safety equipment grounding conductor is good all the way back to the electrical panel the equipment is for all practical purposes safe. (Three wire plug? 2 straight blades, hot and neutral, with a round ground pin. USA)

Here is a stickler though.... More and more equipment may use an IEC plug on their equipment with a 3 wire cord and plug. If the the IEC plug is inspected you may find there is only 2 blades, the hot and neutral. No equipment ground contact. In this case the equipment was built with double insulated AC power wiring. The equipment grounding conductor of the power cord is not used.

The reason for the standard IEC plug,(minus the ground pin), on the back of the equipment? The consumer can use 3 wire cord and plug after market power cords.

Equipment with fixed power cords if the equipment ground is used must have a 3 wire cord and plug. (Hot, neutral, and equipment grounding conductor.)

Equipment with a fixed power cord that uses double insulated AC power wiring will use a 2 wire cord and plug. The neutral blade on the plug will be slightly wider so as it will only plug into the receptacle in one direction. The plug is polarized. This is needed so the switch and fuse protection for the equipment is in series with the hot conductor. Also for the proper AC polarity orientation of the power transformer, that is if the manufacture checks every transformer before installation.... The big boys do... Every power transformer.

The neutral blade on the plug will be slightly wider so as it will only plug into the receptacle in one direction. The plug is polarized. This is needed so the switch and fuse protection for the equipment is in series with the hot conductor.

Remember,this means absolutely nothing if your receptacles are wired wrong.Don't laugh,it happens all the time.

Remember,this means absolutely nothing if your receptacles are wired wrong. Don't laugh, it happens all the time.
Tpreaves (Threads | Answers)

Or if your electrical is wired reversed inside the equipment. This happens too.

Also, some equipment with three prong power cable actually have the ground lifted inside the chassis. I've owned several amps wired this way.

Guess that falls into the category of XLR inputs that are jumped over to the RCA so customers can operate their system in balanced.

In that case it should be referred to as a convenience jack. I've owned several products like this, many people think because the plug is there the unit is properly wired to accommodate it.

Also, some equipment with three prong power cable actually have the ground lifted inside the chassis. I've owned several amps wired this way.
04-25-10: Albertporter

If the amps are UL and or CSA listed then that would imply the AC power wiring of the equipment is double insulated thus meeting UL/CSA standards.

I would rather see the manufacture of the equipment use a C-14 or C-20 plug on their equipment with the ground contact pin removed. That way the consumer/user would know if an equipment grounding conductor was needed for the equipment. Or better yet how about the manufacture be required to print on the back of the unit along with the AC power consumption and Hz if the unit is wired with doubled insulated AC power wiring.

IEC connectors are the only UL/CSA listed plug and socket that I know of that can be used for both 120Vac as well as 220Vac. Can't do that with any NEMA plugs or receptacles. The IEC plug is the only one I know that can be used in electrical equipment and float the equipment ground contact. You could not do that with any NEMA two wire with ground Plug.

So I guess the question to be asked, does my equipment that uses IEC connectors use the safety equipment ground? No equipment ground contact pin in the IEC plug, no....
If the ground contact is present on the IEC plug then the only 100% sure way to know is pull the top cover off the equipment and look inside.

Could use a meter and check for continuity from the equipment ground contact of the IEC plug to the chassis. If the meter shows short then yes the ground contact is connected to the chassis and the equipment ground is needed for safe operation.

If the meter reads infinity/open I would not bet the bank 100% on the reading. Can you say 100% both test probes were making good contact? Pop the hood and look inside....
Or you could contact the manufacture.