RCBO's on a TT system.

[Midwest]

Just thinking this through, what are you putting in the rest of the CU, dual RCD & MCB's?

 

[Leesparkykent]

Dredging up an old thread here.

Shortly have a board change on a TT supply to do. Normally I'd fit 100ma S Type up front and then dual RCD as I don't really see a big benefit in solid neutral RCBO's when you have an upfront RCD.

On this particular job I have a couple of distribution circuits in the consumer unit that I want to achieve good discrimination on. I was thinking of fitting a high integrity (normally use Hager) CU and fitting 2x Hager ADA932U RCBO (1P+N) on what would normally be the 'unprotected ways'.

Hagers website states they can be used in Consumer units but I'm unsure how they fit, being double width. Is it a case of just cutting off the busbar prong where necessary? Seems a bit heath robinson.

Anyone have any better ideas?

I would contact SBS trade sales and tell Dave your requirements. He does a unit that uses two busbars (live and neutral) which the compact RCBOs attach to which are single pole switched neutral. In an ideal world though you don't really want to be supplying distribution circuits via an mcb/rcbo especially if you want to achieve discrimination which you have stated.

 

[Midwest]

Just thinking this through, what are you putting in the rest of the CU, dual RCD & MCB's?

I only ask cos wouldn't there be an S Type in there anyway, still pondering.

 

[mattg4321]

Thanks Lee, the problem I have is the 2 outbuildings supplied have consumer units fitted with a main switch and 3 or 4 MCB's. They are obsolete so not much chance of finding an RCD to swap the main switch with and leave the distribution protected by the 100ma S type and an MCB.

If a fault occurs in either of these 2 outbuildings then I don't want it affecting the main house. If it takes out the 3 or 4 circuits in the outbuilding it's no biggie. We all know in an ideal world you'd have the outbuildings on switchfuses or MCCB's but that's not really necessary here. I just want to try and separate a fault on these 2 circuits from the rest of the house really.

Out of interest what is your go to arrangement for TT supplies? Do you use RCBO's?

 

[Leesparkykent]

Thanks Lee, the problem I have is the 2 outbuildings supplied have consumer units fitted with a main switch and 3 or 4 MCB's. They are obsolete so not much chance of finding an RCD to swap the main switch with and leave the distribution protected by the 100ma S type and an MCB.

If a fault occurs in either of these 2 outbuildings then I don't want it affecting the main house. If it takes out the 3 or 4 circuits in the outbuilding it's no biggie. We all know in an ideal world you'd have the outbuildings on switchfuses or MCCB's but that's not really necessary here. I just want to try and separate a fault on these 2 circuits from the rest of the house really.

Out of interest what is your go to arrangement for TT supplies? Do you use RCBO's?

My go to arrangement would depend very much on the situation, customers budget, room to fit the board, how many and type of circuits etc. I'm not a fan of single pole solid neutral RCBO's tbh. As you are changing the board and if the customer has the budget for it I would still use what I've mentioned above. SBS compact spsn RCBO's for every circuit in a main switch amendment 3 board.

 

[Risteard]

Whilst Hager state that they are suitable for use in distribution boards they are probably referring to installations in other jurisdictions where the use of such devices is common. For example, 1.5 miles down the road from here there is a border, which if crossed you will never see single pole RCBOs used. The DBs used are very different to the ones you are used to seeing in domestic premises though.

Also, as stated, BS EN 60898/BS EN 61009 devices in series are not suitable if discrimination (Selectivity) is required. It won't be achieved under any fault.

 

[mattg4321]

I only ask cos wouldn't there be an S Type in there anyway, still pondering.

Not sure what you're getting at but I'll try! Yes there would be an s type rcd front end, but if you were to get a n-pe fault on either of the outbuildings it would trip the whole installation (including main house) if you used solid neutral rcbo's.

 

[mattg4321]

My go to arrangement would depend very much on the situation, customers budget, room to fit the board, how many and type of circuits etc. I'm not a fan of single pole solid neutral RCBO's tbh. As you are changing the board and if the customer has the budget for it I would still use what I've mentioned above. SBS compact spsn RCBO's for every circuit in a main switch amendment 3 board.

Thanks. Are sbs the only brand that do these does anyone know?

 

[Risteard]

Thanks. Are sbs the only brand that do these does anyone know?

No, there are other brands e.g. Garo.

 

[Leesparkykent]

No, there are other brands e.g. Garo.

I was just looking at meteor electrical at garo RCBO's. Do you know if they make an amendment 3 enclosure out of interest? If im correct I think they may come from Ireland? at http://www.meteorelectrical.com/dis...1/garo-16-amp-30ma-1-module-rcbo-type-b.html#

 

[rich.250]

I believe the hole in the bottom where the fly lead comes from is insulated similar to the 4 mod eaton 3phase rcbo.
It definitely looks like it from the catalogue page here:
http://www.luckinslive.com/product/386509034/Hager-Ltd-Energy-Distribution/ADA916U


Sent from my iPhone using Tapatalk

 

[Risteard]

I was just looking at meteor electrical at garo RCBO's. Do you know if they make an amendment 3 enclosure out of interest? If im correct I think they may come from Ireland? at Garo 16 Amp 30mA 1 Module RCBO Type B| MeteorElectrical.com

I'm not sure if they do an Amendment 3 type enclosure (I doubt it).

AFAIK Garo is a Swedish company, although they do have a base (possibly manufacturing) in Dublin as well. The Garo stuff here all seems to come from Dublin.

Garo gear is never really seen in the north here, but is fairly common in the south.

 

[Midwest]

Not sure what you're getting at but I'll try! Yes there would be an s type rcd front end, but if you were to get a n-pe fault on either of the outbuildings it would trip the whole installation (including main house) if you used solid neutral rcbo's.

See your point now, you've have a can of worms there. Think the problem, is the availability of DP RCBO's, although some have been highlighted. Guess that's done to the introduction of reg 42.1.201, even SN seems a bit sparse. It's fine if you use a particular manufactured product regularly (don't understand why the other manufactures don't do DP/SN), but if the product is not easily available, is a bit of a nightmare if they fail, if you get my drift.

 

[mattg4321]

Exactly, I'd rather stick to Hager - something I know and trust to be honest.

Might give them a call and enquire about the SP+N RCBO. Maybe the busbar prong goes up into a blank chamber behind the N flying lead as rich says. If not I'll pop into the job and look into the outbuildings properly and see if theres a way I can get a 30mA RCD in each of those.

 

[Risteard]

Exactly, I'd rather stick to Hager - something I know and trust to be honest.

Might give them a call and enquire about the SP+N RCBO. Maybe the busbar prong goes up into a blank chamber behind the N flying lead as rich says. If not I'll pop into the job and look into the outbuildings properly and see if theres a way I can get a 30mA RCD in each of those.

I have quite a few two module Hager RCBOs. I believe they do a phase & neutral busbar, although often they would just be wired.

 

[rich.250]

Yes that's the way they suggest.
http://www.luckinslive.com/data/59e...059f/e1391c3c-783b-441b-bf61-905fc0447c35.PDF


Sent from my iPhone using Tapatalk