Makeit go Right
18-07-2008, 01:25 PM
I’d like to prompt some replies starting out with my understanding of this matter:
I have been trying to establish how the 17th Edition impacts on installation of Inverters, which I have previously kept away from RCDs to avoid potential neusence tripping caused by the Inverter (ie, call-backs, alterations etc etc).
I know Daikin have a general note in their installation manuals saying that RCDs should be provided to protect against shock and fire etc, but that seems to be a general aris-covering safety term, rather than for every model in the Daikin range. And when there is a neusence trip situation, they will say see your own electrician, of course.
Along the way, I came across a very useful internet video (from the manufacturer MK) that may be of interest to others, explaining some of the changes to these IEE Regs: www.mk.learninglounge.com/resources/sott17esv.html (http://www.mk.learninglounge.com/resources/sott17esv.html). (I have no connections to MK)
….and some prior text on the subject:
http://www.gadsolutions.biz/electrical/regulations/rcd-and-the-17th.html
Seems to impact very much on receessed wiring (eg, below wall surface or within partitioning etc), which must be protected by an RCD or RCBO.
I came up against this situation when wanting to connect a new circuit into an existing consumer unit for a 10kW Daikin Inverter; the sparkie stuck his chest out and started in with “Must have an RCD…17th Edition…whole system must comply… change board, problems, problems, problems.” Whew! Lots of problems and no real solutions – very unhelpful.
As far as I can see (so far), if installing a new circuit in existing board that does not have RCD protection, and the cable will be recessed into a wall/ceiling/floor (less than 50mm), it should be fed via an RCBO rather than the regular MCB. UNLESS special protection like metal conduit(earthed) is being used to protect the cable, or if run in SWA cable with the steel wire covering properly earthed.
Alternatively run it all as surface wiring so it is not in the ‘recessed’ catogory at all and thus skirt around this issue.
We will be runing an SWA power supply cable, fed via an ‘unprotected’ regular MCB in the existing consumer unit (ie unprotected meaning a circuit without an RCD), in this case because:
a) We will be running the cable surface (ie not beneath the wall surface)
b) The power cable will be an armoured cable, protected with the steel wire earthed, earthed, which would cover the ‘protected cable’ issue addressed in the 17th Edition Regs.
c) The control cable to the wall-mounted controller would be in 2 inches of surface mini-trunking.
# Anyone come up against these 17th edition issues already and resolve it elsewise?
# Any comments on the SWA cable as a way of working around the RCD issue?
# Presumably any cable run in surface trunking would avoid the issue.
# Has anyone been installing RCDs with inverters and have useful comments on this?
(Note: A similar thread has some related info, prior to 17th Edition: http://www.refrigeration-engineer.com/forums/showthread.php?t=12125)
I have been trying to establish how the 17th Edition impacts on installation of Inverters, which I have previously kept away from RCDs to avoid potential neusence tripping caused by the Inverter (ie, call-backs, alterations etc etc).
I know Daikin have a general note in their installation manuals saying that RCDs should be provided to protect against shock and fire etc, but that seems to be a general aris-covering safety term, rather than for every model in the Daikin range. And when there is a neusence trip situation, they will say see your own electrician, of course.
Along the way, I came across a very useful internet video (from the manufacturer MK) that may be of interest to others, explaining some of the changes to these IEE Regs: www.mk.learninglounge.com/resources/sott17esv.html (http://www.mk.learninglounge.com/resources/sott17esv.html). (I have no connections to MK)
….and some prior text on the subject:
http://www.gadsolutions.biz/electrical/regulations/rcd-and-the-17th.html
Seems to impact very much on receessed wiring (eg, below wall surface or within partitioning etc), which must be protected by an RCD or RCBO.
I came up against this situation when wanting to connect a new circuit into an existing consumer unit for a 10kW Daikin Inverter; the sparkie stuck his chest out and started in with “Must have an RCD…17th Edition…whole system must comply… change board, problems, problems, problems.” Whew! Lots of problems and no real solutions – very unhelpful.
As far as I can see (so far), if installing a new circuit in existing board that does not have RCD protection, and the cable will be recessed into a wall/ceiling/floor (less than 50mm), it should be fed via an RCBO rather than the regular MCB. UNLESS special protection like metal conduit(earthed) is being used to protect the cable, or if run in SWA cable with the steel wire covering properly earthed.
Alternatively run it all as surface wiring so it is not in the ‘recessed’ catogory at all and thus skirt around this issue.
We will be runing an SWA power supply cable, fed via an ‘unprotected’ regular MCB in the existing consumer unit (ie unprotected meaning a circuit without an RCD), in this case because:
a) We will be running the cable surface (ie not beneath the wall surface)
b) The power cable will be an armoured cable, protected with the steel wire earthed, earthed, which would cover the ‘protected cable’ issue addressed in the 17th Edition Regs.
c) The control cable to the wall-mounted controller would be in 2 inches of surface mini-trunking.
# Anyone come up against these 17th edition issues already and resolve it elsewise?
# Any comments on the SWA cable as a way of working around the RCD issue?
# Presumably any cable run in surface trunking would avoid the issue.
# Has anyone been installing RCDs with inverters and have useful comments on this?
(Note: A similar thread has some related info, prior to 17th Edition: http://www.refrigeration-engineer.com/forums/showthread.php?t=12125)