I'm head scratching abit but I'm sure I'm right

[oharaf]

Just been reviewing R1+R2 for 2 lighting circuits, both gave me readings of 1.3 ohms.

Is this within an acceptable range, I have been used to getting less than 1ohm but these circuits are fairly large.

If it is not okay it doesn't matter as I'm going back tomorrow, I'm wondering if I have forgotten to null the meter.

It was get late when I did these readings

cheers chaps

 

[GaryMo]

Sounds fine, circuit around 43M in lengh assuming 1.5/1.0 t&e.
For example, if you're using 6A type B BS60898 MCB then you'll need to ensure maximum earth fault loop impedance will be lower than 6.4ohms. You're well within, assuming your Ze reading is as it should be!

 

[oharaf]

Hi Garymo, sorry its me I was looking at the bloody ring final Max. Permitted Zs whilst thinking about the lighting

I obtained Ze by inquiry prior to starting the job, of course the DNO say it is 0.8 for TNs and 0.35 for TNCs, lazzy b@stards.

However to put my mind at rest I am going to measure it again myself as well as redo my RCD trip times, forgot to write them down, ejit

Cheers anyway, to say I have a degree in maffs and 12 years paper work from teaching I don't half do some stupid things, it must be nerves, peoples lives and all that. Sparking is a seriously responsible job

 

[GaryMo]

Sparking is a seriously responsible job

Amen brother!

 

[Adam_151]

Cheers anyway, to say I have a degree in maffs

Want to try and explain Fourier analysis to me in a way that I can understand


(Though I think I'd have no chance, considering I only have a grasp of very basic calculus )

 

[Taylortwocities]

What's that, cant you sleep or something.

Here you go: http://www.sunlightd.com/Fourier/Introduction.aspx

Will ask questions in the morning....

 

[oharaf]

Refer to Bostock & Chandler, they do lovely Fourier Series calculations.

Never seen it applied to sine waves!!!!