don't use rcbos for TT

[mrloy99]

Manufactors instruction leaflet states {on schneider electric rcbo)
Do not use on installations that require double pole switching eg IT or TT.

 

[telectrix]

can't match that. i only got a couple of zippos.

 

[GLENNSPARK]

can't match that. i only got a couple of zippos.

not much then against my..erm...5 i think ...at the last count...

 

[telectrix]

but i bet you not got a harley davidson one. that's worth 3 "ordinary" ones.

 

[GLENNSPARK]

but i bet you not got a harley davidson one. that's worth 3 "ordinary" ones.

well no...

see when i get them i dont plan on riding out for a week....

it just sort of....happens...

 

[not clever]

Do you know of any manufacturers that make single module double pole RCBO's?

I do & so do you, you'll have to visit the other forum to see & purchase them though.....................

 

[D Skelton]

I do & so do you, you'll have to visit the other forum to see & purchase them though.....................

You've lost me

 

[mrloy99]

What they are trying to say is RCBOs are single pole and should not be used where double pole is required, They are not saying do not use on tt, why would they?

I think they are......In a TT installation neutral is also classed as a line conductor,And as such if isolation to a particular circuit is required for maintenance or alteration we are supposed to be able to isolate both poles without having to knock the whole installation off via the mainswitch RCD. I am thinking that double pole CBs could be the answer(rather than dp rcbo's) I know that they are available,and you are still 30ma protected via main switch rcd. I'm a wee bit surprised mr Niceic hasn't made an issue about this before.

 

[D Skelton]

I think they are......In a TT installation neutral is also classed as a line conductor,And as such if isolation to a particular circuit is required for maintenance or alteration we are supposed to be able to isolate both poles without having to knock the whole installation off via the mainswitch RCD. I am thinking that double pole CBs could be the answer(rather than dp rcbo's) I know that they are available,and you are still 30ma protected via main switch rcd. I'm a wee bit surprised mr Niceic hasn't made an issue about this before.

Because it isn't an issue. DP isolation is all that is required on a TT installation, it doesn't say where. Also, a neutral is never a line conductor.

 

[Knobhead]

Oh dear Tony! Carrying out electrical work in a house without being NICEIC registered! Don't be suprised when the Part P police come a'knocking! A cowboy now as well as a Yorkshireman, it just keeps on getting better and better!

There's a way around it. As I'm retired I'll get Glenn to do it for me

 

[Engineer54]

Originally Posted by mrloy99
. I am thinking that double pole CBs could be the answer(rather than dp rcbo's) I know that they are available,and you are still 30ma protected via main switch rcd. I'm a wee bit surprised mr Niceic hasn't made an issue about this before.

Far more sensible to have an all RCBO (SP+N) CU, than a couple of RCD's and a rack of DP MCB's, on a TT installation!!

Also have you considered the size that 10 circuit DP CU will be?? You'll be looking at providing at least a 26 way CU, including the DP isolation switch and 2 X RCD's, and that's not allowing for say a couple of spare ways for the future!! ...You won't be purchasing one of them for 50 odd quid!! lol!!

 

[Badged01]

There's a way around it. As I'm retired I'll get Glenn to do it for me

Theres a load of guys off here offering to do work for free ...... you just may have to put on your little tutu and pad out your chest some more

 

[not clever]

You've lost me

SBS supply trade only with true DP compact single mod rcbo's.
I thought you had seen them on the other forum, there's loads of photos of them in use.

 

[mrloy99]

Because it isn't an issue. DP isolation is all that is required on a TT installation, it doesn't say where. Also, a neutral is never a line conductor.

Sorry meant to say live..rather than line, neutral IS classed as a live conductor.
And without getting too ---- about the whole thing....We have to consider all possible scenarios.
We may wish to do work to a particular circuit without turning off the whole board.It is unlikely that all circuits have isolation after the board. eg lighting circuit with 2way switching
In TT situations neutral is not considered to have a RELIABLE connection to earth(unlike TN.where neutral and earth are joined at the service head)It is possible for the neutral to have a higher potential than earth .Removing the assumed neutral from the neutral bar is not recommended also due to a few possibilities,eg borrowed neutral or neutral in the wrong terminal in the neutral bar.
This voltage may only be a few volts and is unlikely to kill you but an unexpected tickle while working over the stairwell in a house could cause a fall.

 

[mrloy99]

Far more sensible to have an all RCBO (SP+N) CU, than a couple of RCD's and a rack of DP MCB's, on a TT installation!!

Also have you considered the size that 10 circuit DP CU will be?? You'll be looking at providing at least a 26 way CU, including the DP isolation switch and 2 X RCD's, and that's not allowing for say a couple of spare ways for the future!! ...You won't be purchasing one of them for 50 odd quid!! lol!!

Dunno about that!!!
The dp cb's I was using today(in an IT installation)were single module,same phisical size as normal cb's(general electric)

 

[Engineer54]

Dunno about that!!!
The dp cb's I was using today(in an IT installation)were single module,same phisical size as normal cb's(general electric)

That's true, but then most journeyman electricians don't know that they even exist.

I know that a guy is importing them from here (China) on another forum. How about giving us a link to these GE single module DP breakers, for everyone to see....