300Ma 4 Pole Rcd - Pme Supply?

[steptoe]

I'm afraid that is wrong, only a time delay RCD allows discrimination, 

Think about the location,

This is NOT a domestic install, 

Forget about any other RCD that may, or may not be fitted, what is the purpose of the 300mA RCD,?

And think about earthing type on agricultural premises. 

 

[Andy™]

sharpend and essex1, thank you on your understanding rather than jumping down my neck like others......

Ive now read 705 in the regs which is backed up by your previous post......if your not using it everyday you cant implement it and fully understand it as much as one would like. I guess this makes me a useless spark does it and I should put the tools down!

The purpose of the 300ma is to allow discrimination of rcd's downstream,or have i got that wrong aswell?

not knowing every regulation doesnt make you useless, however you should already know the basics of what most of it is, then look up relevant section as and when required.

 

[Sharpend]

Fair comment I would agree with that Andy

Could say ahem it's horses for courses!!

 

[Essex1]

You get used to it on forums don't worry and don't take it personal. People get brave behind a keyboard

I was always taught. A good electrician should be able to find the answer. A good college will teach you how to navigate the book not learn it. The more you do in a particular area the more second nature it becomes.

Forums for me are a great place to see how others do. There is no shame in not knowing. I am not afraid to look stupid as Sharpend will confirm.

 

[NozSpark]

LOL that's why the regs are there,,, for you to refer to when needed.. None of us know all the regs inside and out.

When thinking about why the RCD is there don't think about it's value too much,,, think about what it's doing

 

[Blue Duck]

Am I allowed to give a clue via the medium of youtube?

 

[Sharpend]

I can confirm that Essex is happy to be stupid? Mind if you ask duck then I'm not far behind!!!

 

[Essex1]

I can confirm that Essex is happy to be stupid? Mind if you ask duck then I'm not far behind!!!

Oi!

I never said I was happy about it.

 

[Sharpend]

Sorry!!! Thought Essex was a happy place :C

 

[Essex1]

Essex is the best county in this beautiful country.

 

[jimmybobbob]

As I understand it...the RCD is there for ADS, (like all circumstances) Employing a TT system requires an RCD to meet disconnection times due to the high impedance values, right?

When I said about discrimination down stream...a 30mA should trip first at x 1, also at times 5 (150mA being lower than 300) thus eliminating the type s?

 

[Sharpend]

Ohhhhhhh shuuuuuuuuuuuuuuutup!

Jim I think steps point is going over your head? Think animals?

 

[Essex1]

As I understand it...the RCD is there for ADS, (like all circumstances) Employing a TT system requires an RCD to meet disconnection times due to the high impedance values, right?

When I said about discrimination down stream...a 30mA should trip first at x 1, also at times 5 (150mA being lower than 300) thus eliminating the type s?

You need other things to meet ADS also.

 

[Andy™]

but if you have a fault current of 1a, then which trips first...

i dont think you fully understand how RCD discrimination works

 

[Blue Duck]

I thought it was 100ma for animals?

I know nothing of agricultural installations as I work in the city. been in some real pig styes though....

 

[jimmybobbob]

in addition to RCD's for ADS...earthing and bonding conductors are needed?!

The RCD is employed to protect the life of the animals as they are more susceptible to electricery than humans right, just as the it would in any other installation, I got this from the word off...

I also appreciate that the time delay does what it says on the time...the delay. Isnt this calculated by a percentage added onto the original value which gives the split second delay?

 

[jimmybobbob]

300mA is also employed for fire protection..

 

[Blue Duck]

Bit late now. ohh well......

msl1:   

https://www.youtube.com/embed/sXYa_qklKPc?feature=oembed




I remember the thing about 100mA being for protection of livestock (and TT systems) because most domesticated animals have four legs and therefore are in better contact with the ground so they do not require 30mA protection either that or we care about them less than humans?.

Not sure if that is quite correct but how I remember it.

 

[NozSpark]

300mA is also employed for fire protection..

For/on what though?

 

[apprentice87]

Agricultural premises!!!

john..