newto this,just want to say hello,and if anyone can tell me if i can ask quiestions on this page

[RCBO]

just trying to get started on this site.

 

[Wilko]

Hi there RCBO !
Yes, you may ask questions and likely you'll get some answers too

 

[RCBO]

hi ,im struggling 80% rule of thumb, is this a question ok to ask, I don't want annoy anyone,

 

[Octopus]

80% of what?

 

[RCBO]

80% of what?

I'm trying to understand why this formula is applied to protective devices from the regs, and on site guide has 1.2, applied, Y, please if u can explain please

 

[Strima]

80% of maximum permitted Zs when verifying a circuit?

 

[Leesparkykent]

I'm trying to understand why this formula is applied to protective devices from the regs, and on site guide has 1.2, applied, Y, please if u can explain please

To account for conductor operating temperature at 70 degree C. When testing the conductors will be near room temp. The resistance increases with temp by a factor of 0.004 per degree. If the room temp is 20 degree C there is a 50 degree C difference between room temp and conductor operating temp when fully loaded. 50x0.004=0.2 which equates to 20 percent.Reducing the 100 percent values by 20 percent is the same as multiplying by 80percent. You should be verifying that the Zs meets the 80% values other wise you may not be achieving the required disconnection times due to conductor operating temperature and consequently ADS.

 

[RCBO]

80% of maximum permitted Zs when verifying a circuit?

bless u m8, so can u give me a example on ring final circuit r1 r2,how this value is applied to protective devices in domestic consumer board

 

[RCBO]

To account for conductor operating temperature at 70 degree C. When testing the conductors will be near room temp. The resistance increases with temp by a factor of 0.004 per degree. If the room temp is 20 degree C there is a 50 degree C difference between room temp and conductor operating temp when fully loaded. 50x0.004=0.2 which equates to 20 percent.Reducing the 100 percent values by 20 percent is the same as multiplying by 80percent. You should be verifying that the Zs meets the 80% values other wise you may not be achieving the required disconnection times due to conductor operating temperature and consequently ADS.

thank you very much, ur help is fantastic, may I put u in a scenario,on a domestic

 

[Leesparkykent]

thank you very much, ur help is fantastic, may I put u in a scenario,on a domestic

?

 

[buzzlightyear]

they

hi ,im struggling 80% rule of thumb

their you go .

 

[RCBO]

than

they View attachment 40562their you go .

haha,nice one,lol

 

[telectrix]

t

they View attachment 40562their you go .

there

 

[Pete999]

bless u m8, so can u give me a example on ring final circuit r1 r2,how this value is applied to protective devices in domestic consumer board

r1 and r2 are end to end resistances of the Line conductor and cpc

 

[telectrix]

mornin' pete.

 

[Pete999]

mornin' pete.

Mornin Tel, how are things with you?

 

[telectrix]

fine, Pete. was over Altrincham yesterday, connecting a 3 phase fridge compressor so the fridge guys could commission , plus some 600 x 600 LED panels, in a shop. finishes for 1.00pm and met up with another forum member who was working a mile away. pint and a burger in the nearest pub. day off today unless something comes in.

 

[Pete999]

fine, Pete. was over Altrincham yesterday, connecting a 3 phase fridge compressor so the fridge guys could commission , plus some 600 x 600 LED panels, in a shop. finishes for 1.00pm and met up with another forum member who was working a mile away. pint and a burger in the nearest pub. day off today unless something comes in.

Good day then?

 

[telectrix]

yep. gotto go back 1/2 day next week to complete a rfc when client has cleared a small area in shop. at present it's running as a radial with the end of cable wago'd .

 

[Pete999]

yep. gotto go back 1/2 day next week to complete a rfc when client has cleared a small area in shop. at present it's running as a radial with the end of cable wago'd .

Conduit job ore T and E?