Changing a garage 20A radial to a 32A ring

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Hi, tried to find a similar thread but nothing was quite as specific.

I've got a CU in a garage with a 20A radial in 2.5mm T&E feeding 4 double sockets.

I plan to put the put the washing machine in there (already has a dryer and a fridge freezer) to make some kitchen space.

My slight concern is nuisance tripping (especially if something else gets plugged in) and so I wanted to make the circuit a ring by adding a run of 2.5mm back to the CU from the final socket.

I can then change the 20A mcb to a 32A mcb.

I'll test all continuity and earth resistance at the CU connection point on a multimeter.

The garage is fed from the house CU on a 40A which is RCD protected.

1. Is this Part P notifiable? This is an existing circuit so I'm guessing not but it seems vague. I'd like to do this simple job myself.

The other option would be to add a new radial for the washing machine but as this would be a new circuit so that's definitely notifiable.
 
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.... I plan to put the put the washing machine in there (already has a dryer and a fridge freezer) to make some kitchen space. .... My slight concern is nuisance tripping (especially if something else gets plugged in) and so I wanted to make the circuit a ring by adding a run of 2.5mm back to the CU from the final socket. .... I can then change the 20A mcb to a 32A mcb. .... The garage is fed from the house CU on a 40A which is RCD protected.
That all sounds fair enough.
1. Is this Part P notifiable? This is an existing circuit so I'm guessing not but it seems vague.
Opinions will vary. Some will say that, even though there is an existing circuit, changing the MCB to one of higher rating (and/or converting a radial to a ring) constitutes a 'new circuit', hence notifiable. I personally would probably not take that view, but who am I to know?!
The other option would be to add a new radial for the washing machine but as this would be a new circuit so that's definitely notifiable.
Indeed.

Kind Regards, John
 
The other option would be to add a new radial for the washing machine

Maybe a dedicated radial for the freezer with it's own RCD ( or RCBO ) at the main consumer unit. Snag is that if the freezer trips thet RCD you will have no indication until you notice they are defrosting. Hence it is a good idea to supply a frequently used item or lamp from that circuit.
 
Maybe a dedicated radial for the freezer with it's own RCD ( or RCBO ) at the main consumer unit.
A possibility, but that would definitely be notifiable, and would leave the OP with only 20A for all the rest of his appliances etc.
Snag is that if the freezer trips thet RCD you will have no indication until you notice they are defrosting. Hence it is a good idea to supply a frequently used item or lamp from that circuit.
Indeed - and that's a reason why I've never been a fan of dedicated circuits for freezers (unless there is a temperature-triggered alarm). I also think the 'reason' for having a dedicated freezer circuit is rather over-played. I have personally never experienced an RCD trip whilst the house was unoccupied, and think that it must be a very rare occurrence (and a risk for which many/most of us are paying insurance premiums).

Kind Regards, John
 
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Hi, tried to find a similar thread but nothing was quite as specific.

I've got a CU in a garage with a 20A radial in 2.5mm T&E feeding 4 double sockets.

I plan to put the put the washing machine in there (already has a dryer and a fridge freezer) to make some kitchen space.

My slight concern is nuisance tripping (especially if something else gets plugged in) and so I wanted to make the circuit a ring by adding a run of 2.5mm back to the CU from the final socket.

I can then change the 20A mcb to a 32A mcb.

I'll test all continuity and earth resistance at the CU connection point on a multimeter.

The garage is fed from the house CU on a 40A which is RCD protected.

1. Is this Part P notifiable? This is an existing circuit so I'm guessing not but it seems vague. I'd like to do this simple job myself.

The other option would be to add a new radial for the washing machine but as this would be a new circuit so that's definitely notifiable.
Ye, sounds like a plan. That's what i would do, nice and easy job for the weekend !

DS
 
As to Part P that's up to you. I will not comment.
I would also question testing with a multimeter, I know that the regs say 200 mA to test resistance and 500 volt for insulation, but the old meters used a fair current to measure loop impedance and as a result became quite warm, however the new ones use under 15 mA so as not accurate one would think? The EZ150 plug in tester is down to 9 mA. I have considered measuring loop impedance with a multimeter however the main thing about the propriety testers is speed, when we test we have to run current from line to earth and line to neutral, if the earth is not good enough then it could cause a shock during the test, the limited time and other safety's built in features, although it may be possible to measure the loop impedance with a home made set up, it could not be done safely.

As to RCD tripping in an empty house, I have just dumped the contains of my freezer due to that happening. As far as protecting against the RCD tripping this is hard, I would have a year ago said using RCBO's reduces the chance of tripping, mainly as mother has 4 RCBO's in the kitchen which have only ever tripped when using the RCD tester, however now the rest of the house is supplied by two RCD's and they have not tripped either, I do think it is caused by spikes on the supply, and am aware I live next to a welder, can't actually say it is his welding, but when they trip may be on average once a year, they reset with problem, so it does seem trip due to something on the supply line rather than some thing in the house, could be a thunder storm. Although the tester may show an RCD as being good or faulty, I have had RCD's trip with no good reason, and swapping them stopped the tripping, all 30 mA RCD's are not equal.

When living in the property a simple rechargeable torch on the freezer supply is really all that is required, they auto light with a power cut for around 4 hours and over that food is lost anyway.

However for a freezer in the main, volt drop is a problem, OK new inverter models don't have the same problem, but although run they use less than 1/2 an amp, on start they can draw 10 amp, and if there is a volt drop the motor can stall, there is a overload built into the motor so that if restarted before the pressure drops it will trip and try again once trip has cooled, but the overload if it trips a lot will fail.

I personally like the ring final, and I would not hesitate at converting a radial into a ring final, however with a 20A radial if the washing machine did cause it to trip you would soon know, and I don't think it will trip, it is the drying which takes all the power, not the washing, my son had an inverter drive washing machine on a narrow boat, his idea was to have a charger from shore supply to batteries and then an inverter to power washing machine, the inverter failed, and the washing machine would trip the 4 amp MCB on shore supply, he paid extra for a 6 amp MCB and the washing machine did not trip the MCB. It draws 10A when heaters are on, but not on for long enough to trip the 6 amp MCB. So I don't think you really need to make it into a ring.
 
Since the method would include some danger, I don't think it is appropriate to talk about how on an open DIY forum.
Fair enough.

One can obviously estimate the L-N loop impedance (safely!) by simply observing the voltage drop (at the load) when one applies a fairly hefty load to a circuit. I suppose one could 'think laterally' from that in an attempt to estimate L-E loop impedance but, as you imply, it would be potentially dangerous (for others, as well as oneself) and ill-advised, even for someone who 'knew what they were doing' (and it couldn't be done on RCD-protected circuits, anyway).

Kind Regards, John
 
As to Part P that's up to you. I will not comment.
Well I will, because "up to you" is irresponsibly inadequate - it isn't just he who is affected - everybody else who later uses or modifies what he does is at risk if he does not do it properly.

Saying that it is up to him whether he does or does not make reasonable provision in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installations from fire or injury is wrong - it is NOT up to him - it's a legal requirement that he do so, not some optional choice of his.
 
Well I will, because "up to you" is irresponsibly inadequate - it isn't just he who is affected - everybody else who later uses or modifies what he does is at risk if he does not do it properly.

Saying that it is up to him whether he does or does not make reasonable provision in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installations from fire or injury is wrong - it is NOT up to him - it's a legal requirement that he do so, not some optional choice of his.
I was not saying he has a legal right to decide if to comply with Part P, what I was trying to say it is a poorly written document and so all we have for clarification is case law, since the only cases seem to be where there is something very wrong, or some one said they are scheme members when they were not, it is near impossible to second guess what the courts would say, in real terms is a DIY guy gets it wrong, and the LABC find out, they say rip it out again or we will take you to court, and the DIY guy will rip it out, so there is no court case.

I think we all know what should be notified, however until some one is taken to court for fitting a FCU with cable to a fixed socket, we can't say 100% if allowed or not, we know that scheme providers feel it does not required notifying, but they don't make the laws, and it is using BS7671 forming a new circuit. If instead of using a FCU one uses a mini consumer unit, although it is doing the same thing, it seems scheme providers feel that should be notified, however again it would need a court case to verify this. A consumer unit is a type tested distribution unit, and should be used where in the control of an ordinary person, it would lose it's type testing if you were to fit parts not sanctioned by the manufacturers, so if you do that then it is no longer a consumer unit, it is only a distribution unit, we all know if we modify it that does not mean it does not require notification, however as written it may not count, again up to courts to decide, and until some one is taken to court we can argue until cows come home, but still no answer.

To my mind we all know what we should do, but it is up to each one of us, to read the published paperwork, and make up our own minds, I see no point in trying to reword what the documents say, it is up to you the reader to make up your own mind as to what is allowed, it is not up to the forum members to try and say what the law says, it is up to person doing the work to read it and make up his own mind.

As it stands if I make a 4 way socket on an extension lead and plug it in my kitchen that does not require notifying, however if I put a couple a screws in the wall and fix it to the wall out of the way of any spills on the counter and use some cleats to hold the cable out of the way, then technically it becomes fixed, so I should notify the LABC before I do it. I think even the LABC inspectors would say don't be daft, however in Wales in theory you should.

I am really not interested in going through what is and is not required, that's up to the poster, he can read just as well as me, and he can also decide when clearly it does not make sense and does not really require notifying, with the 4 way extension lead if I buy it then it's type tested so I don't need to notify when using it. Blagdon still market cables for garden type tested so don't require notifying, OK in England the law has changed, but Part P was not written by the Welsh assembly, it was an English law which the English realised had gone OTT so modified it, but left the old one in force in Wales.

You will note the poster has not set his location, so how can we really tell him what to do?
 
ok my thoughts as a chippy
my washing machine is about 1800w or around 8amps but only during the heat cycle that lasts perhaps 5- 10 mins over the 60 min cycle with the average being sub 200w the rest off the time
my tumble dryer is similar at around 1900w at just over 8amp but cycles down to around 60/30 and zero percent quite quickly within a drying cycle off perhaps 30 mins so iff you start a wash then put on the tumble after 15 mins the max you will reach is about 10 amps
the maximum i can reach is about 17 amps with all drawing the maximum
in general diversity would fully cover my tumble and washing machine and possibly a 2ah kettle
we need to remember modern appliances are less power hungry than the appliances we bought 20 years ago
 

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