RCD 3PHASE

[Sid1968]

Some advice please.
A warehouse has a new distribution board fitted. Very nice all schneider breakers and board.
3 Rcbos single phase breakers but the 3 phase breakers are just MCBs

Shud they be RCBOs??

Not mentioned any observations on the the EIC

 

[333rocky333]

Not sure you can get 3 phase Rcbos to fit Schneider or any other boards, normally you would fit a 3 phase Rcd in a seperate enclosure, wired in series after the Mcb, not all circuits need to be wired to a RCD anyway.

 

[sparkwright]

They probably don't need to be.

No doubt they do some kind of machines, and the cables are probably surface mounted - so no danger of them getting drilled through.

 

[JohnW2]

A warehouse has a new distribution board fitted. Very nice all schneider breakers and board.
3 Rcbos single phase breakers but the 3 phase breakers are just MCBs ... Shud they be RCBOs??

I know very little about (and have no experience of) non-domestic installations but, to state the seemingly obvious, does not the answer to your question depend on whether the 3-phase circuits/loads are such as to require residual current protection?

Kind Regards, John

 

[flameport]

Depends on what those circuits are supplying.
Unlike domestic installs, it's not necessary or even desirable to install RCDs on everything.

Not mentioned any observations on the the EIC

EICs can't have observations, those are for EICRs only.

 

[Sid1968]

Ther arr 3 rollers shutter on 3 x 3phase mcbs and 2 wall sockets 3 phase

 

[plugwash]

As I understand it.

Fixed equipment is not normally required to be RCD protected.

Sockets with a current rating of 32A or less should be RCD protected unless there is a documented risk assessment explaining why RCD protection is not necessary.

Cables concealed in a wall/partition are required to be either RCD protected, incorporate an earthed metal layer, or be enclosed in earthed metal conduit or trunking. In practice wiring in a warehouse is unlikely to be concealed and three phase circuits are normally run with either SWA cable or singles in metal conduit/trunking. So RCD protection is unlikely to be needed for the wiring itself.

Most DB manufacturers don't offer 3 phase RCBOs, Eaton do make one but it's 4 modules wide blocking up one pole of the adjacent way. Schnider don't offer a 3 phase RCBO as a single unit but offer a "vigi" module attatches to the side of a MCB to produce a device equivilent to a RCBO but the resulting combination is 6 modules wide! It's also bloody expensive.

So most of the time if RCD protection is needed on a 3 phase system it makes more sense to use a separate RCD. That RCD may be located in a separate enclosure, in an extension box attached to the DB or in a "combination unit" with the socket.

 

[Sid1968]

Thank u so.much for the advise

 

[ericmark]

We fitted RCBO's well at least an add on that made the MCB into a RCBO back in 2004, but since it took up 6 ways in the board not sure really any better to a MCB and RCD.

 

[Lectrician]

Unlikely the roller doors would require RCD protection. The three phase sockets, if 32amp or less should, unless a “documented risk assessment” is available. A socket that is installed for an intended purpose such as a fixed machine may also have RCD protection omitted.

 

[JohnW2]

A socket that is installed for an intended purpose such as a fixed machine may also have RCD protection omitted.

At least as far as domestic uninstallations are concerned, I seem to recall (but may be wrong!) that that 'dispensation' disappeared in the current edition of BS7671 - to the annoyance of those who wanted to avoid RCD protection of a dedicated freezer circuit.

Kind Regards, John