Exactly the reason why I'll carry on taking figures from table 41.3
Max Zs entry on EIC for an RCD circuit
- Thread starter equitum
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Exactly the reason why I'll carry on taking figures from table 41.3
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Many of the figures given in tabulated form are not exactly the same as the calculated value. Consideration will have been given by the authors (I assume) to this figure and deemed acceptable given that it is 0.01V above the calculated value.
As the content and values of BS7671 are not negotiable, I would therefore consider it non compliant to enter any other figure than that in the current or ammended version.
As the content and values of BS7671 are not negotiable, I would therefore consider it non compliant to enter any other figure than that in the current or ammended version.
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Please note that I edited my post for clarity.
That may be, eq, but, if it came to the crunch, would it be viewed as negligent to enter a lower figure?
That may be, eq, but, if it came to the crunch, would it be viewed as negligent to enter a lower figure?
It's not a statutory document so doubt there would be a come back on us in any form due to entering lower figures and not complying.
In fact, it could go down as a departure under 120.3 - the resulting degree of safety of the installation shall be not less than that obtained by compliance with the regulations.
We now have compliance
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Equitum
I now have the book open in front of me.
Table 41.5 appears in a section under the heading "TT system".
The table itself is titled,
"Maximum Earth Fault Loop Impedance (Zs) To Ensure RCD Operation In Accordance With Regulation 411.5.3......."
All the table is effectively saying is that at a Uo of 230V, an RCD of 0.03A rating will operate effectively up to a maximum of 1667 Ohms.
(As I said before, I don't agree with that figure).
Where on earth does it say, "This is the figure you must enter in any test certificates."?
I now have the book open in front of me.
Table 41.5 appears in a section under the heading "TT system".
The table itself is titled,
"Maximum Earth Fault Loop Impedance (Zs) To Ensure RCD Operation In Accordance With Regulation 411.5.3......."
All the table is effectively saying is that at a Uo of 230V, an RCD of 0.03A rating will operate effectively up to a maximum of 1667 Ohms.
(As I said before, I don't agree with that figure).
Where on earth does it say, "This is the figure you must enter in any test certificates."?
SS,
Yes, table 41.5 is in the section for TT systems. However, as pointed out earlier it is referenced to from the TN systems section (411.4.9).
BS7671 isn't telling you enter the value in table 41.5 as the maximum permited, niether does it say anywhere that the value in any other table or derived from any other calculation must be entered. It is the form that is effectively asking the person completing it a question, to which the answer can be found in BS7671 (In this case 411.4.9), just the same as for any other entry on the EIC where a maximum value is required.
Yes, table 41.5 is in the section for TT systems. However, as pointed out earlier it is referenced to from the TN systems section (411.4.9).
BS7671 isn't telling you enter the value in table 41.5 as the maximum permited, niether does it say anywhere that the value in any other table or derived from any other calculation must be entered. It is the form that is effectively asking the person completing it a question, to which the answer can be found in BS7671 (In this case 411.4.9), just the same as for any other entry on the EIC where a maximum value is required.
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