Extending Cooker Feed - Notifiable?

[scousespark]

The post I was referring to is entitled CU ir Isolator switch in garage.
That describes the standard set up and shows the design process followed started with the load. In that case, there would be no point in fitting a CU.

I have interpreted this thread as Dhutch currently has up to 6 items being fed by an extension lead, including his welder. I am not familiar with the esab 150a and am assuming dhutch has identified the 16A requirement from the manal (or rating plate). In this case, I'd run a dedicated radial for the welder. From a 32A breaker, this doesn't leave much spare capacity for any other equipment fed from an FCU. This is the design I've said is poor.

Dhutch referred to 'the bloke doing the job' in one post and later posted that he'd get the sockets and lights now and the welder supply later.

If it's the former, then notification shouldn't be an issue. If it's the latter, a new circuit will be installed at a later date (requiring notification and a run of SWA).

I'd say the best advice would be to bite the bullet and rewire and fit a CU.

 

[JohnW2]

I have interpreted this thread as Dhutch currently has up to 6 items being fed by an extension lead, including his welder. I am not familiar with the esab 150a and am assuming dhutch has identified the 16A requirement from the manal (or rating plate). In this case, I'd run a dedicated radial for the welder.

If your interpretation/assumptions were correct, then I would totally agree with you. However, he has told us that he is currently running the welder from a 13A socket and, as I said, I suspect that 16A was his estimate of total garage load (welder {OR other equipment} plus lighting).

From a 32A breaker, this doesn't leave much spare capacity for any other equipment fed from an FCU. This is the design I've said is poor.

Again, I would agree that, if he might want to run 'other equipment' at the same time as a welder, particularly if the latter really did require a 16A supply, the proposed design may be inadequate - but, as above, I'm not sure that there are any such requirements. I'm not sure what you're thinking would be fed from an FCU (other than lighting). I would say that whether or not the dsign is 'poor' depends upon the design load, which only the OP could advise us about.

I'd say the best advice would be to bite the bullet and rewire and fit a CU.

If current (or anticipated) requirements dictate that, then I would agree - but, as above, I'm not sure that they do. If one did go down that route, and wanted a reasonable amount of discrimination, I presume one would go the whole hog and run the supply from a switch-fuse, not from the house CU.

It's coming to seem that we don't necessarily disagree very much, but are working on the basis of rather different assumptions about what loads the circuit is being designed to supply.

Kind Regards, John

 

[scousespark]

It would be helpful if Dhutch would come back to clarify what the 16A refers to. It is the nature of the beast in forums, where we can only act on the posts we read.

Ignore the FCU quote, it was a senior moment and I'm sure we all have them.

 

[JohnW2]

It would be helpful if Dhutch would come back to clarify what the 16A refers to. It is the nature of the beast in forums, where we can only act on the posts we read.

Indeed. I imagine he will, since he's been returning regularly to participate in this relatively slow-moving thread (and that's not a 'dig' - just a recognition of the fact that you don't visit the forum all that often).

Ignore the FCU quote, it was a senior moment and I'm sure we all have them.

No problem - I, for one, have plenty of such moments, as I'm sure readers of my posts are well aware

Kind Regards, John

 

[dhutch]

It would be helpful if Dhutch would come back to clarify what the 16A refers to. It is the nature of the beast in forums, where we can only act on the posts we read.

I have been reading the replies.

The main purpose of the thread was to gain a better understanding of what people interpretations of the rules where, in terms of what could be installed without notification, and one option considered was to add a socket on the end of the existing cooker feed, which would if nothing else, allow the garage to be electrically removed from the house. I never thought this was a good option, but it might have appealed if it had reduced other issues.

The garage needs some decent lighting, for which I thought a number of 4-5 ft fluorescents was the best option, prehaps 6, and proberbly a 120w pir controled halogen floodlight at the front. It will then need a number of 13amp sockets around the edge to run powertools, drills, anglegriders, chargers, portable lighting (fluorescent handlight and or flood lgiht), etc and given most of these come with 2-4m leads at best my plan as per other workshops ive used would be to have plenty of double sockets, to remove the need for extensions everywhere. And then the single largest power draw, is the welder. I dont really plan to heat the garage as being a large uninsulated steel clad steel framed afair it dont really see it feasable, although if im doing prolonged fine work and it becomes and issue I might invest in a 2kw halogen heater.

The welder is an Esab Caddy 160i Inverter Mig, spec sheet is below, which if you do the sums (say 150*20.1/0.82) can draw around 16amps, although it is supplied with a 13amp uk plug (actaully a moulded schuko with adapter) and appears to weld of this, through extension leads, perfectly satisfatorally which given its intended and used as highly portable welder, is very usful.

Tech specs for the welder avilable on Esab's website:
http://products.esab.com/Templates/T041.asp?id=179839

Given it appears the cooker feed is 6mm^2 by current preposal would be to extend this to the garage in 6mm^2 SWA, fed from a 40amp mcb in the houses '17th ed' twin RCD protected consumer unit. Then in the garage fit a consumer unit with a pair of 16amp mcbs each powering a radial of 13amp sockets down each side of the garage, and a 6amp mcb for the lighting, which I understand should give some diversity from the 40amp mcb. Alternativly it would be possable to have the lighting as a 6amp fcu off one of the radials. You could also take the supply from a 40amp switchfuse installed along side the house consumer unit, or shunt the first RCD in the house cu over and put the garages MCB between it and the main switch so it would atleast not be RCD protected till the garage consumer unit.


Daniel

 

[JohnW2]

Itmain purpose of the thread was to gain a better understanding of what people interpretations of the rules where, in terms of what could be installed without notification, and one option considered was to add a socket on the end of the existing cooker feed, which would if nothing else, allow the garage to be electrically removed from the house. I never thought this was a good option, but it might have appealed if it had reduced other issues.

Yes, that was my original understanding and, if I understood correctly, at that stage you were thinking of a total 'garage load' of 16A, with the garage being connected to the installation by plugging it in to a 16A socket (fed from the unused cooker circuit) on the outside of the kitchen wall. Is that correct? However,as you say, discussions have moved on from there.

The garage needs some decent lighting, for which I thought a number of 4-5 ft fluorescents was the best option, prehaps 6, and proberbly a 120w pir controled halogen floodlight at the front. It will then need a number of 13amp sockets around the edge to run powertools, drills, anglegriders, chargers, portable lighting (fluorescent handlight and or flood lgiht), etc and given most of these come with 2-4m leads at best my plan as per other workshops ive used would be to have plenty of double sockets, to remove the need for extensions everywhere. And then the single largest power draw, is the welder. I dont really plan to heat the garage as being a large uninsulated steel clad steel framed afair it dont really see it feasable, although if im doing prolonged fine work and it becomes and issue I might invest in a 2kw halogen heater.

Thanks for clarifying - this is obviously closer to scousespark's interpretation than your original proposal. I presume that you would not envisage using more than one of the power tools at once - in particular, not using any other tool whilst using the welder. Is that correct? The heater (which I don't think you've mentioned before), if you got it, would obvioulsy move the goalposts a fair bit (to the tune of nearly 9A).

The welder is an Esab Caddy 160i Inverter Mig, spec sheet is below, which if you do the sums (say 150*20.1/0.82) can draw around 16amps, although it is supplied with a 13amp uk plug (actaully a moulded schuko with adapter) and appears to weld of this, through extension leads, perfectly satisfatorally which given its intended and used as highly portable welder, is very usful.Tech specs for the welder avilable on Esab's website:
http://products.esab.com/Templates/T041.asp?id=179839

In that case, scousespark is right. Even if 'it works', you really shouldn't be running that off a 13A socket - it should be on a 16A socket supplied by its own dedicated radial circuit.

Given it appears the cooker feed is 6mm^2 by current preposal would be to extend this to the garage in 6mm^2 SWA, fed from a 40amp mcb in the houses '17th ed' twin RCD protected consumer unit. Then in the garage fit a consumer unit with a pair of 16amp mcbs each powering a radial of 13amp sockets down each side of the garage, and a 6amp mcb for the lighting, which I understand should give some diversity from the 40amp mcb.

As above, the welder really needs its own 16A socket on a dedicated 16A MCB - and then you could have one or two 16A MCBS supplying radials for the sockets circuits and a 6A one for the lighting. You will certainly get some chance of discrimination between 16A and 40A MCBs, but certainly not guaranteed.

Alternativly it would be possable to have the lighting as a 6amp fcu off one of the radials.

Once you've got a CU in the gararage, you might as well give it its own 6A MCB (unless you run out of 'slots' in the CU).

You could also take the supply from a 40amp switchfuse installed along side the house consumer unit, or shunt the first RCD in the house cu over and put the garages MCB between it and the main switch so it would atleast not be RCD protected till the garage consumer unit.

As previously discussed, if you were to have a garage CU, that would be the best place to have an RCD (with no RCD protection at the house end), to avoid faults in the garage taking out circuits in the house. Using a 40A switch-fuse rather than an MCB in the house would give you a greater chance of discrimination (against 16A MCBs in garage CU), but that would, I think,be about the only advantage (and clearly would be notifiable). If you were going down that (clearly more expensive) route, it would probably make sense to go the whole hog, with, say, a 60A switchfuse and 10mm² cable all the way to the garage, thereby achieving very good discrimination from the 16A MCBs in garage.

Going back to your original reason for posting ('notifiability'), crazy though it might be, it's difficult to argue with BAS's interpreting the Building Regs as excluding all electrical work in a non-flammable outbuilding <30m² floor area from the need to notify, and many would probably agree with him that having a JB in the kitchen (to extend the cooker circuit to somewhere else) is also not notifiable. If one accepts all that, and if you meet the floor area requirements, then extending the existing cooker circuit to the garage, and everything you do within tyhe gragare (including installing CUs etc.) would presumably be non-notifiable - even if I (and many others) probably find that 'very surprising'.

Kind Regards, John

 

[dhutch]

Yes, that was my original understanding and, if I understood correctly, at that stage you were thinking of a total 'garage load' of 16A, with the garage being connected to the installation by plugging it in to a 16A socket (fed from the unused cooker circuit) on the outside of the kitchen wall. Is that correct? However,as you say, discussions have moved on from there.

Indeed, it being a case of a sliding target between what I have currently, and the ideal, bearing in mind costs and the fact I will not be living in the house in question more than say five years.

To put it into context, as said, currently the whole ot (bar a heater) runs of a bod standard 1.5mm 13amp extension lead run under the door. This breaks out into a 6 way cabled tied to the frame of the garage, lighting plugs into this with a switch cable tied to the frame above the 6way, with a few flying 4ways to get power around the cars. Horrable, and only meant to be there tempory just to get a light on while I sorted it, but what with one thing and other, its been 14months and counting.

Thanks for clarifying - this is obviously closer to scousespark's interpretation than your original proposal. I presume that you would not envisage using more than one of the power tools at once - in particular, not using any other tool whilst using the welder. Is that correct? The heater would obvioulsy move the goalposts a fair bit (to the tune of nearly 9A).

Yes, there's only one of me almost all the time, but obviously the lights will be on most of the time, and you can easily have a charger on while welding, and even a small heater, as said, has a large effect.

The welder really needs its own 16A socket on a dedicated 16A MCB - and then you could have one or two 16A MCBS supplying radials for the sockets circuits and a 6A one for the lighting. You will certainly get some chance of discrimination between 16A and 40A MCBs, but certainly not guaranteed.

I could add a another radial to a 16amp socket, or put on on the end of the previously preposed radial, but equally im hesitent to chop of the 13amp plug and fit a 16amp as the welder is moved around and used elsewhere so frequently it would still spend half its time plugged into a 13amp socket with a adapter to 16amp ceeform.

There is also currently a 16amp socket in and enclosure with a 16amp rcbo in it on the wall, not wired to anthing, but could be encorporated if usfull, otherwise its going in the bin or on ebay.

Once you've got a CU in the gararage, you might as well give it its own 6A MCB (unless you run out of 'slots' in the CU).

Thats what I thought, as long as, as you say, you dont run out of slots, or more correctly, find that a smaller box is a lot cheaper.

Daniel

 

[dhutch]

As previously discussed, if you were to have a garage CU, that would be the best place to have an RCD (with no RCD protection at the house end), to avoid faults in the garage taking out circuits in the house. Using a 40A switch-fuse rather than an MCB in the house would give you a greater chance of discrimination (against 16A MCBs in garage CU), but that would, I think,be about the only advantage (and clearly would be notifiable). If you were going down that (clearly more expensive) route, it would probably make sense to go the whole hog, with, say, a 60A switchfuse and 10mm² cable all the way to the garage, thereby achieving very good discrimination from the 16A MCBs in garage.

Going back to your original reason for posting ('notifiability'), crazy though it might be, it's difficult to argue with BAS's interpreting the Building Regs as excluding all electrical work in a non-flammable outbuilding <30m² floor area from the need to notify, and many would probably agree with him that having a JB in the kitchen (to extend the cooker circuit to somewhere else) is also not notifiable. If one accepts all that, and if you meet the floor area requirements, then extending the existing cooker circuit to the garage, and everything you do within tyhe gragare (including installing CUs etc.) would presumably be non-notifiable - even if I (and many others) probably find that 'very surprising'.

Kind Regards, John

If the feed is taken from downstream of one of the two RCDs in the house CU, is there any point in having an RCD in the garage?
If there is an RCD in the garage, is there any point in shuffling the MCB in the house CU to be upstream of the RCDs?

Obviously the cost of fitting a switchfuse, in buying 10mm SWA inplace of 6, and in running the back to the CU rather than the kitchen are significant. And there is also the issue that the house CU and meter etc are at the front of the house, meaning running a cable inside the house would be a massive pain, and running 10mm SWA right round the house to the front wall, would also be very obtrusive on what is otherwise a very clear wall, thinking if nothing else, about resale.

If it was a brick garage, and I was planning to make the house my family home, I would do it in a heartbeat, get a 2post lift in there, some machine tools, pillar drill, band saw, lathe, and a load of heaters in there so I could flash it upto temp in a reasonable amount of time. But realistically, its my first house, living there with two other engineering graduate coleagues of mine i rent rooms to, im almost only every there during week day evenings, and my girlfreind doesnt like the house or area and neather of us intend live in the house long term.


Daniel

 

[JohnW2]

If the feed is taken from downstream of one of the two RCDs in the house CU, is there any point in having an RCD in the garage?

Not really, except as a 'belt and braces' (for garage circuits) in case the one in the house fails. In the case of a fault in the garage, either or both of the RCDs could operate.

If there is an RCD in the garage, is there any point in shuffling the MCB in the house CU to be upstream of the RCDs?

The 'point' would be to avoid taking out all of the circuits on the house RCD in question in the event of a fault in the garage. If it's just a 2-RCD CU (with no provision for non-RCD circuits), then achieving what you suggest would not be straightforward.

Kind Regards, John

 

[JohnW2]

Once you've got a CU in the gararage, you might as well give it its own 6A MCB (unless you run out of 'slots' in the CU).

Thats what I thought, as long as, as you say, you dont run out of slots, or more correctly, find that a smaller box is a lot cheaper.

I don't think price is likely to be much of an issue - CU enclosures are two a penny, even larger ones. For what you're describing, an 8-way would probably make sense - RCD or Main switch (2 modules), welder circut, 2 sockets circuits and 1 lighting circuit adds up to 6, by my reckoning.

Kind Regards, John

 

[dhutch]

The 'point' would be to avoid taking out all of the circuits on the house RCD in question in the event of a fault in the garage. If it's just a 2-RCD CU (with no provision for non-RCD circuits), then achieving what you suggest would not be straightforward.

Fair enough. As there is only one ring main, and the cooker and imersion heater radials are unused, the only circuts on the second of the two RCDs is the upstairs lights and the convervatory, so I dont see it being a huge risk.

Daniel

 

[JohnW2]

Fair enough. As there is only one ring main, and the cooker and imersion heater radials are unused, the only circuts on the second of the two RCDs is the upstairs lights and the convervatory, so I dont see it being a huge risk.

Fair enough.

Kind Regards, John