How to test quality of earth connection ?

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steve_rb

Joined: 17 Feb 2004
Posts: 64

01 Aug 2004 6:32 how to test earth connection

I am using a XRF instrument and I want to be sure earth connection has sufficient quality since instrument has a lot of boards and any discharge can cause disaster. Could experts please advice how I can test my instrument earth connection quality with tools like Ohmeter or oscilloscope.

Steve

sergio mariotti

Joined: 22 Dec 2003
Posts: 467
Helped: 42
Location: Italy

09 Aug 2004 17:21 how to check earth connection

I think you are speaking about the Heart connection on the mains supply line.
If yes, witout a specific instrument, try this, but remember, the operation contain a risk.

1) I assume Your mains is Line+Neutral.
2) I assume the Neutral is "good enough" to have a potential near to 0 V and enough stable during the time.
3) I assume that a some kind of GND contact on the socket is REALLY connected to the Heart, also if with a bad conection. THIS IS FUNDAMENTAL FOR SEFTY !
4) Disable an eventual "differential" circuit breaker (or connect measurement before it).
5) connect AC voltmeter between GND and Neutral (on the socket).
6) ADVISE EVERY PEOPLE INSIDE YOUR BUILDING!!
The following operation is RISK of FOLGORATION !

7) connetc a power load (like a 100W lamp) between Line and GND. Lamp should turn on, read the ACVoltmeter (V1) and DISCONNECT SOON!

Cool

Applying the Ohm law, the GND resistance is Rgnd=V1/(Power_lamp/V_mains)
eg:
V1= 6V
Power_lamp=100W
V_mains=220V
Rgnd= 6/(100/220)=8.2 Ohm, that is good for most applications.

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brmadhukar

Joined: 21 Jun 2002
Posts: 844
Helped: 29

17 Aug 2004 1:44 how to test an earth connection

Hi,
check the earth(absolute) to neutral voltage if possible. This should be less than 10V. Also check the votages with respect to neutral. This should not be more than 10V from the pecification.
Make sure the chassis is connected to the ground/neutral.

B R M