earth loop impedance

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dougal

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hi

I have just bought a tester cheep but when i do the earth loop test it trips the rcd. the only lead i have for doing the test is one with a plug.

how do I do the test?

thanks

craig

 

patspark

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as steptoe said give us a clue what tester have you got my tester has one a setting witch will not trip the rcd you may have the same d lock more info

needed

 
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My old Robin earth loop has 'D Lock' to prevent the Rcd tripping. This works by saturating the Rcd coil with DC. Modern Rcbo's can sense both AC & DC ( largely because lots of new PSU'S can put out DC when working, preventing an Rcd from tripping) I can not use this on Rcbo's and have bought a fluke multi tester now.

Why did you think your meter was cheap ?

 

daryl631

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had same problem with alphatec meter using plug changed to using different plug adapter and it worked ok

 

davetheglitz

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Some older meters were not designed for use with an RCD - probably why it was cheap (I bought an old Metrotest a couple of years ago before I realised this!). Other than buying a new meter the easiest way round this is by calculation. Use the meter to measure Ze at source - no RCD problems there, and then use low ohm meter to measure R1 + Rs (apply short at one end and measure at the other - don't forget to remove the short!) Zs = Ze + R1 + R2.

 
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Also any electrical equipment plugged into circuit gets fried 25 amp current does that.batty
EH????

The "25A" which is so vaunted about, is a pulse on a half - cycle; between phase and earth. Unless the item connected has a functional earth connection ( which you`ve already fried with your insulation test (which chucks more voltage down the line than things were designed to handle.) - it isn`t a problem. 25A is NOT flowing through any connected equipment m8. Common misconception.

 
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Just going by a job i did years ago doing a loop test on a circuit that an electrician had connected a shed into. client was asked to take all appliances out of sockets on circuit. She had said all sockets were empty. Got a call back a next day to say stereo would not work turned out that fuse had blown.

batty

 

steptoe

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EH????The "25A" which is so vaunted about, is a pulse on a half - cycle; between phase and earth. Unless the item connected has a functional earth connection ( which you`ve already fried with your insulation test (which chucks more voltage down the line than things were designed to handle.) - it isn`t a problem. 25A is NOT flowing through any connected equipment m8. Common misconception.
thanks KME Ive been sitting here trying to work this out, never heard of it before except in faulty equipment(which as you say would already fry on IR!)

or in certain industrial, which aint very common either TBH, and I think at that stage people doing that work understand how it works.

;)

 

dougal

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the tester is a seaward sbs7671

I can do the short circuit test but not the earth loop

to do the test at the moment uses a "kettle lead"

there is an option to buy another lead that has the "kettle" plug at one end and three probes on the other But this retails at

 
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I was talking about Robin loop testers with d-lok the small yellow ones. These test at 25 amp for a short period. I don't use mine anymore. I use Di-log 9083p. These test at a lot lower amperage.

batty

 

extension15

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I was talking about Robin loop testers with d-lok the small yellow ones. These test at 25 amp for a short period. I don't use mine anymore. I use Di-log 9083p. These test at a lot lower amperage.batty
And there you are then...

Technology improves......

]:)

 
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