2023 250.36 Impedance Grounded Systems

[@chrisf3875]

Another great explanation, this boy's been doing it since 1990 I still had it in my head as a neutral conductor!! When you have to come to terms about all the wrong things that you were taught. You know you're getting up there..........

[@MrMaxyield]

Ran into one of these at a hospital a few months ago, i admittedly didn't know as much as i wanted to know about the system... Loving this series. Thanks Ryan..!

[@christianopp4613]

I'm getting ready for teaching a 2023 code update class on Friday and you did a great job laying this out thank you

[@WOL76]

I think I’ve seen a system like this on an oil drilling rig

[@ronaldkovacs7080]

On these systems can the impedance device be an inductor or capacitor?

[@nhzxboi]

See them in power plants a bunch.

[@bryankellyM]

I'm surprised no one objected to 250.36(3) being added to the code. It is a common practice in industry to have impedance grounded system for ground fault detection and also have a need for 277V single phase loads (e.g.,, open bay lighting systems.)

[@bryankellyM]

Another example I have seen often is with industrial electric furnaces and ovens. Elements are single phase and controlled via SCR/contacts by zones independently as 277V legs. Transformers tend to be larger (1500KVA or 2500KVA) with impedance grounding to reduce risk/damage during a phase to ground fault.