Testing volt drop

[Guest 004]

How do you guys record the volt drop?
Measurement with volt meter
Calculation with the mVA formula
Other, please state

 

[Amp David]

Calculation before I install circuit then I know it complies

 

[telectrix]

ditto^^^

 

[RWJ]

Third that!!

You can't use a voltmeter....

 

[malcolmsanford]

Calculate the volt drop when your designing an installation, as it is not a requirement of an intial verification

If I was doing a PIR and I noticed say a dim light, or was told that for instance a kettle took ages to boil, or an immersion took ages to cut off, then I would measure the voltage under load.

There is though no where to actually record it on either the EIC or the PIR and schedlue of test results.

Volt drop is covered in section 6 reg 612.14 and section 525.

 

[Guest 004]

I have just done calculation on a 50mm 4 core 3 phase supply, which has a run of 70 metres, by calculation it fails. By measurement it is 226V, so I should tick the verification box, and indeed check my measuring stick!

 

[telectrix]

all depends on what voltage you have at source. if it's 240v you have a drop of 14v. this is over 5%.

 

[malcolmsanford]

As often in our industry calculation rarely mirrors real life. You omitted your Ib part out, what was in on your calculations, and what was the load when you measured the voltage??

 

[Guest 004]

125Amps

No load

 

[malcolmsanford]

Well you can't really measure a volt drop until there is a load on it.

 

[Guest 004]

Well you can't really measure a volt drop until there is a load on it.

So I should turn on the sub circuits, then test again?

 

[malcolmsanford]

If your calculation is telling you that there will be an unacceptable volt drop then yes, if you want to confirm your calcs then you need to have a load on the installation. It will either confirm your calculations are correct or not

 

[Guest 004]

If your calculation is telling you that there will be an unacceptable volt drop then yes, if you want to confirm your calcs then you need to have a load on the installation. It will either confirm your calculations are correct or not

Thanks MM

 

[Golden_Boy]

Third that!!

You can't use a voltmeter....

I can use a voltmeter !


connect load
measure voltage at source


measure voltage at load

take one from the other = voltage drop ????

 

[topquark]

That's rather assuming that your supply voltage is constant, which it isn't