Connecting appliance to live and earth

Thread Starter

Siva Manasan

Joined Nov 14, 2017
10
What kind of breaker would be triggered If I connected a Bulb from Live to Direct Earth?
If I replaced the breaker with an iron nail Would the circuit work just fine?

What is the name of the breaker which triggers, when the current going through the Live is not returned to the neutral?
For the above breaker, what is the minimum current difference needed between live and neutral to trigger it?
 

Reloadron

Joined Jan 15, 2015
4,698
What is the name of the breaker which triggers, when the current going through the Live is not returned to the neutral?
For the above breaker, what is the minimum current difference needed between live and neutral to trigger it?
Depends on where you are located to some extent. Here in the US and North America we seem to favor the naming convention of GFCI (Ground Fault Circuit Interrupt).
When the amount going differs from the amount returning by approximately 5 milliamperes, the GFCI interrupts the current. So about 5 mS with a 2.5 mS trip time (1/40 Second).

Also read the link provided by Externet above.

Ron
 

Dodgydave

Joined Jun 22, 2012
8,576
What kind of breaker would be triggered If I connected a Bulb from Live to Direct Earth?
If I replaced the breaker with an iron nail Would the circuit work just fine?

What is the name of the breaker which triggers, when the current going through the Live is not returned to the neutral?
For the above breaker, what is the minimum current difference needed between live and neutral to trigger it?
Why?
 

Thread Starter

Siva Manasan

Joined Nov 14, 2017
10
Depends on where you are located to some extent. Here in the US and North America we seem to favor the naming convention of GFCI (Ground Fault Circuit Interrupt).
When the amount going differs from the amount returning by approximately 5 milliamperes, the GFCI interrupts the current. So about 5 mS with a 2.5 mS trip time (1/40 Second).

Also read the link provided by Externet above.

Ron
If there was no RCD in the circuit, Would I be able to connect a bulb directly from Live to Earth?
 

Reloadron

Joined Jan 15, 2015
4,698
If there is no RCD or any type of GFCI involved and you connect a lamp (bulb) between mains High and earth ground the bulb will light but that assumes a good earth ground. That is in theory as earth ground is a pretty wide term. This also depends on location and how power distribution is setup making a definitive answer difficult. Personally I would not suggest using ground as a return path. Not a good idea to try.

Ron
 
While we are on the subject, an AFCI or Arc Fault Circuit Interrupter tries to detect loose connections and frayed cords. The GFCI and AFCI functions are usually combined.

A GFCI will detect hot and neutral reversed and a shared neutral.

In the US, it's permissable to use a GFCI receptacle for ungrounded outlets as long as the outlets are labeled that they have no earth ground and GFCI protected.
 

crutschow

Joined Mar 14, 2008
23,761
The bulb likely will light with a connection from the live to earth, if there's no GFCI in the circuit,
but that should never done a practice, as the ground is not designed or intended to carry current.
 

MaxHeadRoom

Joined Jul 18, 2013
19,414
Note:
The NFPA and IEEE recommend a ground resistance value of 5 ohms max. while the NEC 50.56 ensure system impedance to ground is less than 5 ohms.
Max.
 

Phil-S

Joined Dec 4, 2015
138
RCD or Residual Current Device in UK. Used to be ELCB (Earth Leakage Circuit Breaker).
My house is connected to the utility supply using a system called PME (Protective Multiple Earthing) or TNCS (Terre Neutral Combined System).
Only two insulated cables come in, Live and Neutral. The utility company earths the neutral between sub-station and consumer at several points along the distribution network. Neutral is the earth. In the house, earth is split off the neutral to provide the third way in the house wiring (E, N, L). Power (socket outlets) circuits go through an RCD, lighting etc. circuits do not. So effectively, you are connecting appliances to Live and Earth. Personally, I don't like the idea of circuits like lighting, cooker, immersion heater being protected by overcurrent circuit breakers only. I think the logic is that these circuits are "fixed" and need a tool to access them, which implies competence. Socket outlets are a different prospect. Anyone can connect themselves to 240-V AC with a plug and damaged cable, especially with garden tools like mowers etc. that often do not have an earth connection.
 

KMoffett

Joined Dec 19, 2007
2,783
Here is a paper from Univ of Penn. on using earth as a conductor.
It was used many years ago as the telegraph return in distant places.
Max.
In old rural telephone systems in the US, the telephone line was one bare wire on the poles. Ground was the second conductor. As a kid I found out I could throw a wire over the telephone line and hook it to one lead of an old telephone earpiece. Then stick the other lead in the ground, and listen to conversations. ;) Only six families on our section of the system, so not much interesting. My first foray into electronics.
 

DickCappels

Joined Aug 21, 2008
6,005
Within two years of completion of construction all buried electric cables (Cable TV, telephone, 240 VAC, doorbell) stopped working. And to think I actually tipped the electrician once! When the doorbell failed, the real electrician we hired had an inspiration. The connection failed because there was an intermittent connection between the two conductors.

The doorbell was wired to 240 VAC on one side (ouch!) and connected to Neutral through the bell button. His solution: Connect the button terminal that usually went to Neutral to a small grounding rod he drove into the ground near the doorbell button. Imagine the torment those earthworms experienced when the button was pressed. He was otherwise a good electrician. I eventually had another electrician run conduit out to the button, giving those earthworms a break.

My ground fault interrupter breakers trip at about 15 ma. That's painful enough.
 

Reloadron

Joined Jan 15, 2015
4,698
The doorbell was wired to 240 VAC on one side (ouch!) and connected to Neutral through the bell button. His solution: Connect the button terminal that usually went to Neutral to a small grounding rod he drove into the ground near the doorbell button. Imagine the torment those earthworms experienced when the button was pressed. He was otherwise a good electrician. I eventually had another electrician run conduit out to the button, giving those earthworms a break.
During some construction I removed the door bell wiring. I went with a wireless door bell. A little coin cell about once every 1.5 years. I have the receiver programmed to play The Marine Corps Hymn which compliments my Marine Corps door mat. I am getting real fond of wireless stuff.

Ron
 

Berzerker

Joined Jul 29, 2018
549
DickCappels said:
His solution: Connect the button terminal that usually went to Neutral to a small grounding rod he drove into the ground near the doorbell button. Imagine the torment those earthworms experienced when the button was pressed. He was otherwise a good electrician.
This makes me feel better about hiring "so called" electricians
Max you doing side work again?

He might want to know about power piracy.....A nail ???.....Earth ground???
If you have power you have a neutral !
Brzrkr
 
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