Ah that Makes sense, I would of thought it would be cut and dry with regards to exceeding VD, that's what im struggling with
....for a RFC is the design current always 32 or (26) or could you have a design current of 25 but still have it on a 32 amp mcb or rcbo?
So in this case where it is compliant on a 20 amp, compliant in terms or ZS and VD but not reg 433.1.204 it would be a c3.
Would it be a c3 or c2 if it was on 32 amps complied with ZS but VD was 7.5% in your opinion?
Might be a dumb question, but do metal back boxs have an effect on the R2 reading
I feel like they dont as when you times r1 or rn by 1.67 you get the expected r2 of the cable
you would not be concerned with the at 32 amps?
is that because the VD is only a few percent over ? or becasue you doubt they would ever be loaded that much to reach 32 amps?
Regulation 433.1.204 seems kind of dumb where it states the 30 / 32 amps on a rfc
dropping the mcb rating does not make it less safe, does it? I mean you can get 25amp mcb now
I feel like it should mean you can use 32 amps on a ring wired in 2.5mm even though the cable is rated lower than 32...
Learning I have done a level 2 and 3 and working on my NVQ.
I have started working with my dad who is QS and old spark and he brought a new property and has let me test it to get some real world experience before he tests its. ( its empty I cant hurt anyone )
why cant you comply with the regs...
Thanks for the reply its educational to say the least.
I found a ring of 151 meters and one of 135 meters so they are both over the range for VD
The longest one feeds two bedrooms and the shorter one feeds a front room and hallway
Leaving them on 32 amps does not sit well with me.
They meet...
I'm getting there with it but a drop of 22 volts on a rfc is a fail of vd?
So if you used a 16amp mcb on a rfc the formula would stay the same? But in the above case the vd would then comply
What would happen if you exceed VD than say less than 10%
So it would go something like this?
(1.15 + 1.80) / (19.51/1000)
2.95 / 0.01951 = 151 meters
so this to work out the voltage drop it would then be
Voltage Drop = ( mV/A/m ) x L x Ib / 1000
18 x 151 x 32 / 4 = 21744 / 1000 = 21 volts
does not comply with voltage drop
r1: 1.15
r2: 1.80
rn: 1.15
r1r2 0.69
To work out the length of a ring in 2.5mm twin would this be correct
0.69/(19.51/1000) = 35m
or would you use the r1r2 before you divide it by 4?
On a domestic Cu 60 amp would live and nuetral tails cause eddi currents of any significants if the tails were run in sperate metal conduit but then run through the same tails gland at the cu?
IM sure the answer is yes
Old two core cable in a lighting circuit with no cpc at any point
All points had metal fixtures and fittings class1
At two points the live loop had been wired into the earth point of a light fitting one on the downstairs lights woth the bathroom above which when on gave a 130 volts on the...
What would be the solution?
When the ceiling is bonded you can get a very small shock if you touch the panel screws and the metal grid. but testing between the screws to the ceiling reads 0 volts but I'm guessing with a multi meter that reads dc it would give a reading?
if you test from the...
The drivers are class 2 yes
If you test from met to a metal screw on the unit you get any where between 15 to 50 volts
And met to ceiling grid 100v
If you bond the ceiling you get small sparks when the panel touch’s the grid when the circuit is on
Same small sparks if you connect the bonding...
100 volts on a metal ceiling grid when measuring from the Met to the ceiling grid
Only when lighting circuit (led panels ) is on it goes away if the panels are disconnected from the drivers and left on
Each panel has 25 volts from met to screws on the back they are class 2!!
So the voltage...
Purpose is curiosity of my own electrical installation, and why i would have almost a dead short on N-E but with no RCD tripping unless it was a load
My flat has a circuit in it that tests as follows when live cpc and neutral are disconnected from the CU @ 250 volts
ZS 0.45
L-E >200...
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