The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!


2017 NEC and Related
2017 NEC
Now Available!

Recent Posts
Parking lot pole light swap....
by gfretwell
10/24/16 08:46 PM
International Wire Colour Codes
by Tjia1981
10/23/16 12:08 PM
Son of Sparky
by HotLine1
10/20/16 07:43 PM
Speaking of Plugmold ...
by gfretwell
10/17/16 02:37 PM
Broken battery charger? Check for cobwebs!
by gfretwell
10/17/16 02:30 PM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 14
HotLine1 7
ghost307 7
renosteinke 6
Potseal 4
Who's Online
0 registered (), 340 Guests and 4 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#129419 - 02/28/05 12:58 PM what really is an ungrounded system?
unsaint32 Offline

Registered: 08/24/04
Posts: 16
Loc: eden prairie, MN, USA
Q 1) What is the purpose of ungrounded system. Is it not to trip the circuit breaker when

the first fault occurs? (for more controlled deactivation?)

Q 2) In a grounded system, having one conductor connected to earth provides the reference

for steady voltages supplied to loads. How is stable voltage accomplished in an ungrounded


Q 3) Actually, there is no such thing as an ungrounded system, right? (Because an ungrounded

system is capacitively grounded.. whatever that means)

Thanks for your answers


#129420 - 03/01/05 02:00 AM Re: what really is an ungrounded system?
Trumpy Offline


Registered: 07/05/02
Posts: 8532
Loc: SI,New Zealand
Welcome to ECN,
Most Electrical systems throughout the world have a reference to Earth.
This is mainly for Safety reasons.
It is so that there is a limit on the Line to Ground voltage.
Let's face it, these days if you're not young, you're old - Red Green grin

#129421 - 03/01/05 04:20 AM Re: what really is an ungrounded system?
pdh Offline

Registered: 01/20/05
Posts: 354
I wouldn't trust an ungrounded system where the primary has a higher voltage than the secondary to be very stable. Impedance grounding is generally adequate for a one fault tolerant system. And you'd need that grounding point to set an alarm to know where there is a fault.

I wouldn't even trust an article 411 system (411.5(A) requiring it to be ungrounded) unless it is isolated with a grounded electrostatic shield between primary and secondary, or has 2 transformers with an intermediate grounded loop at the final secondary voltage.


ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals