Second Opinion on Modification to Existing Circuit

[lozarus]

Came into work today with a fairly urgent requirement to install an instant hot water handwash unit in a small commercial kitchenette/servery - circa 2.8kw. Of course, it's in a right difficult area.

As the handwash is over 2kW, I'd ideally like to follow OSG advice and give it it's own circuit. However, pulling new cables back to the "local" DB isn't really viable with the timescale I have, so I've had a look at what exists at present and I have a few options. None of them will be perfect and I'm struggling to establish the best / safest - or indeed a concrete reason to pick none of them, so wondered if I could put my thoughts out there.

The entire thing has been terribly designed from the outset. There's just one twin socket present that runs the pannini press (2.8kw) and the milk chiller. This is just a 20a radial - don't intend to touch this as it's already got some significant load on it and I've discovered it seems to have been wired by someone with their teeth and in SY which looks like it's 1.5.

The only other circuit - also wired in SY - is a 6mm radial to a 32a socket. The 32a socket has a flylead in 4mm flex, adapting it down to a single 13a socket where it runs a coffee machine (again 2.8kW)....so I figured this would be the most likely contender to alter

I considered terminating the SY using a proper gland (even though I'd rather not use the stuff as it's entirely inappropriate) into a glav knockout box and creating a "hybrid" or "lollipop" RFC back to the 6mm - or indeed a 4mm radial from this point to supply a single socket for the coffee machine, and then an FCU for the handwash

It just feels wrong - because it won't be a standard circuit - but in my head I know it will be perfectly safe. I don't like the SY but my hands are a bit tied with this one.

Am I worrying over nothing? Currently doing my NVQ so having a slight heightened awareness here....

Thanks

 

[littlespark]

Timescale mimescale!

If it can’t be done to your design properly in the time… then it needs more time.

whether these suggestion are right or wrong, you are designing the circuit and ultimately putting your name to it.

 

[MJPD29]

None of these options would be viable and I wouldn’t go ahead with them. As above, if there is no time to do it right then don’t do it at all.

 

[lozarus]

Thanks. I needed that kick up the backside.

New dedictaed circuit going in tomorrow. It takes what it takes.

 

[davesparks]

As the handwash is over 2kW, I'd ideally like to follow OSG advice and give it it's own circuit.

Wherabouts in the OSG does it say this? I rarely use the OSG for anything and am interested as that's not mentioned in the regulations.

Ignoring the OSG for a minute the regulations only make a recommendation that loads over 2kW be on a dedicated circuit rather than a ring final circuit. There's nothing to say that each apllimace should have it's own circuit, just that the circuit should be dedicated to the aplliance(s) rather than being a general use circuit.

If that 32A socket is not required then it could be removed and that circuit turned into a standard 32A radial to feed the 2 appliances.

This only leaves the issue of the SY cable which would be up to you as the person who has actually seen it and how it is installed to decide what is best.

 

[Dustydazzler]

Aren't we getting all European with our 'Dedicated' Circuits for individual appliances, where over there its regulation to install everything on its own individual circuit and have it all labelled nicely on the consumer unit with pretty little pictures.

 

[lozarus]

Wherabouts in the OSG does it say this? I rarely use the OSG for anything and am interested as that's not mentioned in the regulations.

Ignoring the OSG for a minute the regulations only make a recommendation that loads over 2kW be on a dedicated circuit rather than a ring final circuit. There's nothing to say that each apllimace should have it's own circuit, just that the circuit should be dedicated to the aplliance(s) rather than being a general use circuit.

If that 32A socket is not required then it could be removed and that circuit turned into a standard 32A radial to feed the 2 appliances.

This only leaves the issue of the SY cable which would be up to you as the person who has actually seen it and how it is installed to decide what is best.

As you imply - it isn't in the OSG. This was an error on my part having been through it last night. I think it's in an appendix of the brown book - but as you say, it is just a reccomendation. I just try to make sure any work I do takes the 'reccomendations' into account. There was a small RFC going around the seating area - I would have considered making an engineering judgement and breaking into this, espescially considering the occasional load of the instant water heater - however the shopfitters have already loaded it up with 3 heated displays so I wasn't happy.

I think as you say, my intention was to modify the existing 32a radial. However it becomes too complex. The datasheet for our Scolmore/Click sockets suggests the terminals can't take more than 2x4mm or 4x2.5 - so I wouldn't have been comfortable putting 2x6 in to create a traditional radial - thush I was looking at creating a hybrid circuit. However, as you also point out, also the SY - my conclusion was that I wouldn't have designed and installed the circuit in this way - so I'm not happy taking responsibility for it. I do have the shopfitters EIC for it but I disagree with it - so all things considered I've designed a new 20a radial from a spare way for the appliance and informed them of the increased time required

 

[lozarus]

Aren't we getting all European with our 'Dedicated' Circuits for individual appliances, where over there its regulation to install everything on its own individual circuit and have it all labelled nicely on the consumer unit with pretty little pictures.

Back to that days of BS 546 circuits around the house. 1x 15a fuse to a 15a socket etc.

 

[Dustydazzler]

Back to that days of BS 546 circuits around the house. 1x 15a fuse to a 15a socket etc.

Still come across immersion heaters with a 15amp plung and socket in very old houses , awesome things

 

[Pretty Mouth]

What are the concerns with using the existing SY cable in this case? (I don't know much about the stuff, have only come across it a couple of times)

 

[lozarus]

What are the concerns with using the existing SY cable in this case? (I don't know much about the stuff, have only come across it a couple of times)

The majority of it complies with European DIN standards, not BS. Thats not to say it can't be used, just that we have to satisfy ourselves that it meets or exceeds British standards.

Also in a lot of cases the manufacturer states its a control cable, not a distribution cable - so theres the manufacturers instructions side of things.

In my specific instance the braid has been taped off and not connected to the CPC and not d9ne with a proprietary SY gland - so hasnt been installed correctly

That said ive never actually seen it installed correctly...

 

[Dustydazzler]

Isn't SY cable a signal cable or something ? only to used to connect up certain things like AC units, and not to used as a distribuition cable

 

[nicebutdim]

In my specific instance the braid has been taped off and not connected to the CPC and not d9ne with a proprietary SY gland - so hasnt been installed correctly

That said ive never actually seen it installed correctly...

Even in industrial applications the braid never seems to be glanded correctly, with it cut off and both ends of cables shoved into stuffing glands.

I hope this is highlighted in periodic inspections - especially when only recently installed.

 

[lozarus]

Even in industrial applications the braid never seems to be glanded correctly, with it cut off and both ends of cables shoved into stuffing glands.

I hope this is highlighted in periodic inspections - especially when only recently installed.

Yeah - its sods law that ive ended up coming back to this location - I posted a thread a few months back whereby I disagreed with the contractor installing this and was trying to code it. Despite everything we've said here it was quite hard to do...

 

[nicebutdim]

Yeah - its sods law that ive ended up coming back to this location - I posted a thread a few months back whereby I disagreed with the contractor installing this and was trying to code it. Despite everything we've said here it was quite hard to do...

I half remember that discussion, but not the outcome. Surely at least one end needs to be earthed? I've never used SY in a professional capacity and have been briefly familiarised with its glanding as it forms part of the AM2.