How to connect a earth leakage detection GFCI/ELCB?

Discussion in 'General Electronics Chat' started by bobdxcool, Mar 23, 2015.

  1. bobdxcool

    Thread Starter New Member

    Feb 12, 2012
    18
    0
    My specifications are as follows:
    2 in phase 120V lines
    1 Neutral
    1 Ground

    So, I should use a 240V GFCI, right ?

    http://www.trci.net/products/shock-shield/user-attachables/high-power-gfci

    This is the one I plan to use. 23250 003-1 GFCI

    So, connections would be connecting one 120V line to the line wire on gfci, 2nd line wire to the second line wire on GFCI and neutral to neutral and ground to ground.

    IS that correct ? Or, am I going wrong anywhere ?
     
  2. DickCappels

    Moderator

    Aug 21, 2008
    2,658
    632
    You should use the GFIC that is designed for the voltage supply to which you plan to attach it. If your mains voltage is 120 volts, you should use a 120 volt GFIC. A 240 VAC GFIC might not work and was almost certainly not certified f0r normal operation at 120 VAC.
     
  3. bobdxcool

    Thread Starter New Member

    Feb 12, 2012
    18
    0
    So, I should use a 120V GFCI for my application ? Although I have 2 120 volt in phase lines ?
    So, I should use a 120 Volt 4 wire 1 phase GFCI, where I can two in phase 120V lines, neutral and ground.
    I was thinking of connecting 2 120v lines in series to the 240V GFCI. Will that work ?
     
  4. DickCappels

    Moderator

    Aug 21, 2008
    2,658
    632
    To be on the safe side I am going to pass on this and wait until somebody who has dealt with your situation can respond.
     
  5. sdowney717

    Member

    Jul 18, 2012
    387
    13
    If you have 240vac when measured hot to hot (phase wires) with both hot lines and 120 vac with a hot and a neutral, then you use a dual pole 240vac GFCI breaker in a house panel.
    That way ground faults will trip if either hot phase line current flow does not match returning current flow.

    Looking at the wiring directions
    http://www.trci.net/media/76173/cci_safety_products_brochure_34.pdf

    Type B, is the same idea that I see displayed in their wiring diagram.

    Question is are you needing just 120 or 240 vac ?
     
  6. crutschow

    Expert

    Mar 14, 2008
    13,028
    3,237
    I'm confused. :confused:
    First you talk about 1 neutral and 1 ground, and then you talk about 2 120V in-phase lines and a 4 wire GFIC.
    So how many wires do you have?
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,553
    2,375
    I took the OP to mean the typical 120-0(N)-120 plus ground N.A. supply.
    As per the one shown in post #5.
    Max.
     
  8. #12

    Expert

    Nov 30, 2010
    16,320
    6,818
    (2) 120 volt lines that are in phase with each other are the same as each other. You would measure zero voltage between the (2) lines that are in phase with each other. Why do you think you are working with 240 volts if you can't measure 240 volts with any combination of the wires you have to work with?
     
    Reloadron and DickCappels like this.
  9. Reloadron

    Active Member

    Jan 15, 2015
    963
    232
    Before you worry about using a GFCI you really need to understand how they work. This is from out friends at NEMA and is one of the better explanations out there.While I don't know your location here in the US mains power enters a residence in most cases as 240 VAC "Split Phase". This makes for 240 VAC Line to Line and 120 VAC Line to Neutral. The two 120 VAC lines (240 volts split phase) are 180 degrees apart from each other. Appliances using 240 VAC will vary. There are electric stoves, electric hot water heaters, electric clothes driers, residential HVAC systems and other appliances. You would not for example use a GFCI on the lines going to an electric clothes drier because on many driers the motor runs on 120 VAC from one line to neutral and the heating elements run on 240 VAC line to line. You need to better explain exactly what you are attempting to do and why to determine GFCI requirements if any.

    Ron
     
  10. boatsman

    Senior Member

    Jan 17, 2008
    165
    390
    I don't know if this should be posted as a new thread, but anyway here it is. I was taught many years ago that if a 3 phase 380v earth leakage current breaker were connected in series it could be used on a single phase 220v system with double the sensitivity. That is , instead of the normal tripping current of 30mA the new tripping current would be 15mA. The connections would be input at the bottom terminals at N and T and output from the top of N and T to the bottom input at R and S and the final output at the top at R and S. I tried out this configuration by connecting this up to my garden irrigation system and tested it by pressing the test button. Unfortunately this had the result of also causing the ELCB in the main fuse box to jump as well. Why did this happen? Surely if the sensitivity of the garden circuit was much lower than the main circuit why should the latter jump?
     
  11. Reloadron

    Active Member

    Jan 15, 2015
    963
    232
    Never heard of that. Typical GFCI current trip limits here in the US are in the 4 to 6 mA range. The current trip limits are determined by:

    Thinking about GFCI operation I don't understand how placing the phases of a 3 phase GFCI breaker in series would lower the trip limits?

    Ron
     
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