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    Zs values when there is additional RCD protection

    Hi everyone, Consider we have an RCD+MCB protection for a circuit. if we follow the tables for Zs values of a 10A, MCB, type C, the maximum value shall be 1.75 Ohm, this happens when 100A current flows ( as per MCB breaking curve). When the RCD disconnects the circuit in much less current, why...
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    Earth Fault Loop Impedance Test for lighting circuits

    The reason for doing this test is to verify that Zs is low enough and at the time of earth fault, current would be high enough to trip to breaker(MCB).Correct? Where I work ( in Dubai) we have 100mA RCDs for all lighting circuits. So practically, if there is any earth fault, the RCD would...
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    Earth Fault Loop Impedance Test for lighting circuits

    yeah, I am not sure it if it necessary to to it. on the GN3 guideline, it has been mentioned the recommended points to be tested are at: - origin of the installation -distribution boards -accessible socket outlets -extremity of radial circuits 1571029063 On the GN3 guideline, it has been...
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    Earth Fault Loop Impedance Test for lighting circuits

    Hello guys, Do you do Earth fault loop impedance test for lighting circuits during periodic inspection ? do you measure it at the lighting point? what is the percentage of lights you test? Thanks alot in advance
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    UPS protection

    Hi everyone, would be great if you can share your experience on type of protection devices recommended on UPS system feeder/upstream? as you know, in some type of critical installations such as hospitals, bank servers,..etc, the client does not want to see UPS loads gets cuts off in no...
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    Max Zs value for MCCBs

    Thank you. Or probably better( cheaper) to contact more commonly used MCCB manufacturers and ask for the data.
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    Max Zs value for MCCBs

    Thank you. had heard about Amtech but didn't know it has Zs values for breakers as well :thumbsup:
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    Max Zs value for MCCBs

    Thanks, yes we do follow BS regulations here. So I need to contact the manufacturer :thumbsup:
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    Max Zs value for MCCBs

    Hi Guys, in an installation with one main Distribution board and several submain-DBs, do when you measure Zdb on a submain-DB incomer? and do we need to verify the Zdb value with the upstream protection device?( for example, a 250A, MCCB on the MDB outgoing). If yes, how can I get the max Zs...
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    Commercial sub mains exceed max zs of mccbs

    Hi Guys, in an installation with one main Distribution board and several submain-DBs, do when you measure Zdb on a submain-DB incomer? and do we need to verify the Zdb value with the up stream protection device?( for example, a 125A, MCCB on the MDB outgoing). If yes, how can I get the max Zs...
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    Testing ACBs during Periodic inspection

    I guess they want to make sure the springs would work properly and disconnects the load if they want to manually switch it off . also in case of a fault, it trips safely. which if I am not wrong, means all the procedure that you have mentioned shall be done and it is better to be done by a...
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    Testing ACBs during Periodic inspection

    I am not sure.I believe they prefer to deal with just one company for testing the whole installation
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    Testing ACBs during Periodic inspection

    Hello everyone! Has anyone been asked to test the main building incomers like ACBs as part of Periodic Inspection? If yes, do you give this part of the work to 3rd party? and what is the process and how you verify the report? some of my bigger clients are asking for this test to be done. Thanks...
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    Editable IET model forms - full set **UPDATED 2019**

    Thank you so much, downloaded them from your new post :thumbsup::thumbsup::thumbsup:
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    Zs and IR pitfalls

    Thanks alot. It makes it more confusing as we have a TN-S system with additional local earthpit(s) in the property
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    Zs and IR pitfalls

    Hi Guys,we use RCD+MCB in every circuit over here( TN-S system). what would be the max Zs? Do you refer to MCB table?
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    Editable IET model forms - full set **UPDATED 2019**

    I am facing the same problem
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    Editable IET model forms - full set **UPDATED 2019**

    Hi Steve! Are the links still available to download, It gives me ' URL not Found' message once I click on the links. Thanks you, Arash
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