Bizarre Orange electrical plug

Found a building with multiple plugs that I’ve never seen before. A quick Google search revealed what the orange color designates. But I couldn’t find any information on the shape of the outlet. It’s in a retail setting quite a old location that has seen many remodels over the years. The shape of the receptical is three curved holes. That’s the best way I can think of to describe it. I have a pic but couldn’t figure out how to include it with this post. Would appreciate any insight you could lend. Thanks.

Without seeing it, it sounds like it might be a twist-lock type of plug. Is it like this?


Yes! That looks right what are those used for? Are there tools that have cords that end in a special plug? Otherwise how would you plug anything into one without an adapter which would kinda defeat the purpose of the twist lock function.

At one time an orange receptacle was indicative of an isolated ground(IG) system. That later changed to an orange triangle on the device. In most applications orange devices (now with the orange triangle) are still used to indicate IG devices although IG systems are somewhat obsolete.

I still find them in Medical buildings/offices from time to time.

Isolated ground twist lock.

If it is orange, it is an isolated ground. An isolated ground receptacle can reduce electrical noise, but if installed incorrectly, it can create a dangerous installation. This receptacle differs in construction from its self-grounding counterpart. The grounding terminal for an IGR is insulated from its metal mounting yoke. Most commonly used on areas where sensitive equipment, audio equipment, computers, etc are in use.

The three curved holes are a twist lock… plug is inserted and turned… it then can not be accidentally unplugged if cord is pulled.

Someone said it above, these are still used in some counties. Medical and dental facilities mostly, where you don’t want to accidently “pull the plug” on a piece of vital equipment. The primary reason for the IG is to reduce electrical “noise” that medical equipment can be very sensitive to.

The twist lock can also provide higher current or even three phase supply. Here is a hand link with several styles…

Really? You will find them in use in data centers, etc. There are many very valid reasons to still have isolated grounds, in particular where pieces of equipment will be connected together, and they feed from separate sub-panels. I still see them in new larger buildings, but typically only in 40,000 to 60,000 sq foot buildings or larger. I do not see a lot, but still do see them in brand new buildings designed by electrical engineers. I did a building late last fall which was less than a dozen years old, and had isolated grounds in it.

I do admit they are not need as much for computers as in the past, as the power supply on computers has evolved. But there are a lot of more sophisticated and expensive equipment than computers. The larger and more complex the building the greater likelihood you may see them.

Good points about these types of receptacles. I agree that these can be hazardous if installed improperly because they may be unintentionally left ungrounded.
The use of an orange receptacle is no longer an acceptable means of identifying an IG receptacle (I remember installing hundreds of them twenty years ago) now it can be any color but it must have an orange triangle.

There are some limited applications where they’re still used but for the most part they’re obsolete due to the changes in computer technology. Engineers are finally seeing the waste of money that it is designing and installing some of these IG systems. We used to install an IG receptacle at every desk for a computer to be plugged in. :roll:

True… but still same electrically.

True… you do not see them at office desks like you used to… but they are still used and for good reason … but not for personal computer protection as was once common.

But I do still see them in data centers where servers and larger equipment is installed on racks.