Unbalanced final ring

[Steve-S]

I have seen a final ring that had the heavy appliances on one leg (L1). Drawing 19.5 amps in total, one leg (L1) was drawing 82% of the 19.5 amps of current. If the ring went up to 32 amps the 2.5mm cable would in theory be just safe enough under the 27 amp maximum.

My question is, if 32 amps worth of appliances were drawing current on L1 would the 82% be reduced as there would be more resistance on L1, so more current would be sent around L2, reducing the 82%?

I have not seen any tests on this. It would be interesting to see some.

 

[littlespark]

Is this a practical situation?

The general norm for 2.5mm rfc is a 32A OCPD, what is on the circuit just now?

If it’s 20A, I’d be worried it wasn’t an ring at all




For your question though….. if you’re pulling the full load of 32A, is the ratio of what percentage of the load goes back on which leg different?

That would be down to how far each leg is from the board, not the load or cable size.

A high load (say 32A) midpoint on a ring, you would expect it to be 50/50 (16 on each leg)
The closer to the board on one leg the further from the other…. But even if your load was only 1m from the board, some of that load would still return on the longer side of the ring. It would never be 100% one way.

The 82% you measured is relative to your particular installation, with its particular lengths of cable.
That percentage will increase as the load moves away from the board, and increase as it gets nearer.

 

[PS Electrics]

I have seen a final ring that had the heavy appliances on one leg (L1). Drawing 19.5 amps in total, one leg (L1) was drawing 82% of the 19.5 amps of current. If the ring went up to 32 amps the 2.5mm cable would in theory be just safe enough under the 27 amp maximum.

My question is, if 32 amps worth of appliances were drawing current on L1 would the 82% be reduced as there would be more resistance on L1, so more current would be sent around L2, reducing the 82%?

In theory yes because resistance is dependant on cable temperature and cable temperature is effected by load current.

I have not seen any tests on this. It would be interesting to see some.

There are calculations for this that would be interesting I guess to play around with.

I would imagine the effect would be very tiny though to be of no practical use.

 

[Steve-S]

In theory yes because resistance is dependant on cable temperature and cable temperature is effected by load current.


There are calculations for this that would be interesting I guess to play around with.

I would imagine the effect would be very tiny though to be of no practical use.

This is an actual installation with a complete ring with no bridges or breaks. 50 square metres of floor area with 21 sockets, all double except two singles. It is a finished flat, so no simple opportunity to run say 4mm on leg one (L1) from the breaker in the CU to the first two or three sockets, to ensure that section of the ring does not overheat.

Calcs are fine but I thought someone on Youtube or whatever may have done a demo of this sort of thing, the sort if thing John Ward does, or real live written test data in an actual house. Of the 19.5A drawn on the full ring 15.99A was going through one leg. It is borderline as 82% of 32A is 26.24A, if the ring is on max load, just inside the 2.5mm cable's maximum rating.

 

[DefyG]

I'm confused as to what you are referring to as one leg (L1)? If it is a ring (RFC) there is no 'one leg'!
Ideally the loading should be equally spread around the ring but in practice if part of that ring goes by way of a kitchen its possible it may take more of the load, but not all of the current flow as some would still flow around the ring.
As per #3 there are calculations but if you stick to the OSG recommendations, should be fine as they take into account the calculations.

 

[Steve-S]

I'm confused as to what you are referring to as one leg (L1)? If it is a ring (RFC) there is no 'one leg'!
Ideally the loading should be equally spread around the ring but in practice if part of that ring goes by way of a kitchen its possible it may take more of the load, but not all of the current flow as some would still flow around the ring.
As per #3 there are calculations but if you stick to the OSG recommendations, should be fine as they take into account the calculations.

There are two conductors off the breaker L1 and L2 they meet in the middle forming a ring.

I am not after advice on how to install a ring which you are giving. I explained that the ring is already there with no opportunity to easily amend it. Where the ring snakes around the place is a mystery at present. I was after some real life test data that proves or disproves the 82% of the ring's current on one leg may shift one way or the other when the ring is on full load - 32A from 19.5A. Many here may know pointers to such data or vids, or give some real life experiences of such situations.

 

[Avo Mk8]

Calcs are fine but I thought someone on Youtube or whatever may have done a demo of this sort of thing, the sort if thing John Ward does, or real live written test data in an actual house. Of the 19.5A drawn on the full ring 15.99A was going through one leg. It is borderline as 82% of 32A is 26.24A, if the ring is on max load, just inside the 2.5mm cable's maximum rating.

Here's sort of a simple demo, but not in a house, of what you were asking:

View: https://youtu.be/FNgTnFs7f5o?feature=shared

I note the word 'leg' is also used in the video!

My take is that many appliances don't constantly run at maximum demand, they generally have thermostats that turn on & off, or the appliance is used for a short time (eg kettle, hob, food processor, toaster, etc). Even dishwashers, washing machines or tumble dryers only draw full load while their heating elements get stuff up to temperature, and then the thermostat manages consumption. So the heating effect on ring final cables would not perhaps be as great as instantaneous measurements might suggest. I guess you would need to monitor over time to find out.
Also worth mentioning that fixed loads over 2kW, such as electric radiators, should be on a dedicated radial circuit, not the ring.

 

[Steve-S]

Here's sort of a simple demo, but not in a house, of what you were asking:

View: https://youtu.be/FNgTnFs7f5o?feature=shared

I note the word 'leg' is also used in the video!

My take is that many appliances don't constantly run at maximum demand, they generally have thermostats that turn on & off, or the appliance is used for a short time (eg kettle, hob, food processor, toaster, etc). Even dishwashers, washing machines or tumble dryers only draw full load while their heating elements get stuff up to temperature, and then the thermostat manages consumption. So the heating effect on ring final cables would not perhaps be as great as instantaneous measurements might suggest. I guess you would need to monitor over time to find out.
Also worth mentioning that fixed loads over 2kW, such as electric radiators, should be on a dedicated radial circuit, not the ring.

Thanks v much. I had a look.

a) He had a total load of 8.56A with one heater on the socket nearest to the CU. The leg the heater was on drew 7.1 A, which is 82.94% of the total load.

b) At the end he had a ~5kW load which is 21.73A at 230v which is 2.53 times more than the first test in a). He measured 16.43A on the loaded leg which is 75.61% of the total load - down 7.33%. So the percentage draw dropped. At 75% at 32A full load leg 1 would draw 24.2A, within the max current limit of the 2.5mm cable - that is if it stayed at 75.61% of course.

So the percentage of the load on the loaded leg, leg 1, did go down the greater the total load. But to drop only 7.33% the total load was increased 2.53 times.

In my situation, it is: washing machine, kettle, dishwasher, microwave, tumble dryer, all clustered in the kitchen on the first leg from the CU. On a total load of 19.5A 82% is coming from one leg, on not too off a total load to the final test in the Efixx vid. In my situation there is obviously more resistance on leg 2 than in the Efixx test. A full test with all appliances on has not been done, as some were not there to test.

The final conclusion is that the test by Efixx indicates that the higher the load the less the percentage draw on leg 1 with more current coming around the back from leg 2. So in my situation if the total ring load went to near 32A the percentage of the load on leg 1 would drop just below what the cable is safely capable of holding.

Anyone agree?

 

[Steve-S]

Here's sort of a simple demo, but not in a house, of what you were asking:

View: https://youtu.be/FNgTnFs7f5o?feature=shared

I note the word 'leg' is also used in the video!

My take is that many appliances don't constantly run at maximum demand, they generally have thermostats that turn on & off, or the appliance is used for a short time (eg kettle, hob, food processor, toaster, etc). Even dishwashers, washing machines or tumble dryers only draw full load while their heating elements get stuff up to temperature, and then the thermostat manages consumption. So the heating effect on ring final cables would not perhaps be as great as instantaneous measurements might suggest. I guess you would need to monitor over time to find out.
Also worth mentioning that fixed loads over 2kW, such as electric radiators, should be on a dedicated radial circuit, not the ring.

Yes, the likelihood of all appliance being on and all drawing max current simultaneously for long periods is slim - diversity. But Murphy's Law says if it can happen it will happen.

 

[Avo Mk8]

There are learned articles on the web showing load profiles of kitchen appliances, that show many of them do not consume their maximum rated current all the time - in fact some don't consume that current most of the time.
In your example of washing machine, kettle, dishwasher, microwave, tumble dryer, you would need a pretty frenetic family to be operating all of them at once, and if they were, those such as the kettle or microwave would be off again (at full power) within a few minutes, otherwise the food in the microwave would be on fire, or the kitchen full of steam!

Try applying diversity to loads for a more realistic estimate.
And if you have the time, here's a comparison of calculations vs. actual:

View: https://youtu.be/PnagUPuFlak?feature=shared

 

[DefyG]

Where the ring snakes around the place is a mystery at present.

So in my situation if the total ring load went to near 32A the percentage of the load on leg 1 would drop just below what the cable is safely capable of holding.

As the installation is a mystery at present you dont know what the installation method is, you wont know what derating factor to apply and therefore current the cable is safely capable of carrying before overheating.

 

[PS Electrics]

I have seen a final ring that had the heavy appliances on one leg (L1). Drawing 19.5 amps in total, one leg (L1) was drawing 82% of the 19.5 amps of current. If the ring went up to 32 amps the 2.5mm cable would in theory be just safe enough under the 27 amp maximum.

My question is, if 32 amps worth of appliances were drawing current on L1 would the 82% be reduced as there would be more resistance on L1, so more current would be sent around L2, reducing the 82%?

I have not seen any tests on this. It would be interesting to see some.

I assume you are investigating this because of some issues?

My only concern regarding the installation would be if the ring was not installed to best practice. I was always taught to try as best as possible to run the cables so sockets are spaced out evenly along the ring rather than wire them in a straight line with one long dead return leg so that loads are balanced along the ring as best as possible, obviously though with bad luck the ring can still be skewed with loads on one side of the ring.

As Avo Mk8 said though I cannot see a scenario where this should be an issue but since you are investigating this something must be awry?

 

[Pretty Mouth]

This question piqued my interest, so I played around with the numbers, and concluded that the heating effect on the cables doesn't make much difference to the proportion of current that will flow down the short leg vs the long leg.

Example ring final:

30m long
Cable rated at 20A
30A load all at one point exactly 10m along one leg.

Initially, the current will flow through the legs in the proportion 20:10

(10/30) X 30 = 10A flowing through the long leg 20m
(20/30) X 30 = 20A flowing through the short leg 10m

As the short leg of the ring is loaded to its full rating, it will theoretically heat to its full 70 degree operating temperature, and its resistance would increase by approx 1.2 times. Some heating should also occur in the long leg, but a lot less, so for simplicity, lets assume no heating of the long leg.

Now the current should flow in the proportion 20:12

(12/32) X 30 = 11.25A flowing through the long leg
(20/32) X 30 = 18.75A flowing through the short leg

So in this example, the extra resistance caused by the heating of the short leg, caused 1.25A to 'redirect' down the long leg. Which is very little, about 4% of the total 30A.

 

[Steve-S]

I assume you are investigating this because of some issues?

My only concern regarding the installation would be if the ring was not installed to best practice. I was always taught to try as best as possible to run the cables so sockets are spaced out evenly along the ring rather than wire them in a straight line with one long dead return leg so that loads are balanced along the ring as best as possible, obviously though with bad luck the ring can still be skewed with loads on one side of the ring.

As Avo Mk8 said though I cannot see a scenario where this should be an issue but since you are investigating this something must be awry?

No issues. I saw the ring could be unbalance by the proximity of the CU to the kitchen cluster. As I have said the ring is in, in a fished place. My quick test was as I reported also with a total ring resistance of 1.2 ohms on L & N with a multimeter. The Efixx vid appears to indicate that the 2.5mm cable will not draw more than the max permitted current when just under 32A. With diversity the likihood of drawing a full load for an extended period is slim.

When there is no option to round robin the sockets to balance with an unbalanced ring looking likely, it is best to run on leg 1 4mm cable to the cluster of high current drawing sockets and then 2.5mm for the rest.

This question piqued my interest, so I played around with the numbers, and concluded that the heating effect on the cables doesn't make much difference to the proportion of current that will flow down the short leg vs the long leg.

Example ring final:

30m long
Cable rated at 20A
30A load all at one point exactly 10m along one leg.

Initially, the current will flow through the legs in the proportion 20:10

(10/30) X 30 = 10A flowing through the long leg 20m
(20/30) X 30 = 20A flowing through the short leg 10m

As the short leg of the ring is loaded to its full rating, it will theoretically heat to its full 70 degree operating temperature, and its resistance would increase by approx 1.2 times. Some heating should also occur in the long leg, but a lot less, so for simplicity, lets assume no heating of the long leg.

Now the current should flow in the proportion 20:12

(12/32) X 30 = 11.25A flowing through the long leg
(20/32) X 30 = 18.75A flowing through the short leg

So in this example, the extra resistance caused by the heating of the short leg, caused 1.25A to 'redirect' down the long leg. Which is very little, about 4% of the total 30A.

Nice. That 4% seems to fall in line with the Efixx test, which dropped by 7.33%.

 

[Steve-S]

As the installation is a mystery at present you dont know what the installation method is, you wont know what derating factor to apply and therefore current the cable is safely capable of carrying before overheating.

Looking at the construction, a lot of hollow partition walls, it looks like 22-23A for the 2.5mm. Borderline. Relying on diversity for sure.

In my own place all heavy appliances are on their own radials: w/machine, oven, hob, dishwasher, boiler (so it is not dropped out by other circuits faults). I only use a toaster, rice cooker, TV, laptop and small fridge and vacuum on the final ring, which IS also unbalanced on an AFDD, but nothing there to overload it if I tried.

 

[mainline]

it is best to run on leg 1 4mm cable to the cluster of high current drawing sockets and then 2.5mm for the rest.

The best way is to design it properly in the first place.

 

[Steve-S]

The best way is to design it properly in the first place.

What I wrote was quite clear.

 

[Pretty Mouth]

I also ran the numbers for another example ring, 101m long, 20A cable rating, 20A spot load at exactly 1m along one leg. I won't reproduce all of the working outs, but initially: 19.802A through the short leg, and once the cable had heated: 19.763A. Almost nothing in it.

 

[DefyG]

19.763A. Almost nothing in it.

Unless method 101 for example, where max ccc permitted for 2.5 t&e is 17Amps, it becomes an issue!

 

[Pretty Mouth]

Unless method 101 for example, where max ccc permitted for 2.5 t&e is 17Amps, it becomes an issue!

For clarity, my posts in this thread focus on the original question, regarding the effect cable heating may have on the flow of current through an unbalanced ring. My examples show how the current may be distributed through the circuit under certain unusual loading situations, before and after cable heating, and my last example shows that under the stated specific circumstances, cable heating has almost no effect on that.

 

[Steve-S]

What has alerted me, to some surprise, is how out of balance a final ring can be, which must be more typical in British homes than we think as heavy current drawing appliances are clustered. This was not a big problem in the 1960/70s. I measured 82% on one leg while Efixx measured 83%. Previously most I measured were 70-30 at most, giving 22.4 amps on one leg - just inside the max for the cable for the majority of installations. Fitting a ring with sockets in round robin (1st socket on leg 1, 2nd socket on leg 2, 3rd socket on leg 1, etc) will solve a balance issue, but this method can be quite impractical and a heavier in use of cable increasing costs.

This points us to that final rings should be all in 4mm, or 4mm on one leg to the clustered heavy current drawing sockets and then 2.5mm for the rest at least, for many reasons. In a normal house/flat I would lean to put as many appliances as possible on a full 4mm ring protected by an AFDD; diversity taken into account of course. A 3kW-ish oven & low current drawing induction hob on a 4mm radial and of course the immersion, if one on premises, on its own 2.5mm radial. Maybe more economical having the immersion on 4mm as final ring and oven/hob will be on 4mm so cable being cheaper all on the same purchased drum. At TLC a 100m drum of 4mm is £147 (£1.47 p/m), with 100m drum of 2.5mm £72 (£0.72 p/m), about twice the price, but £1.03p on a 25m drum. Costs of 4mm could drop in cable costs as only using one final ring in 4mm. Worth thinking about.

 

[Pretty Mouth]

What has alerted me, to some surprise, is how out of balance a final ring can be, which must be more typical in British homes than we think as heavy current drawing appliances are clustered. This was not a big problem in the 1960/70s. I measured 82% on one leg while Efixx measured 83%. Previously most I measured were 70-30 at most, giving 22.4 amps on one leg - just inside the max for the cable for the majority of installations. Fitting a ring with sockets in round robin (1st socket on leg 1, 2nd socket on leg 2, 3rd socket on leg 1, etc) will solve a balance issue, but this method can be quite impractical and a heavier in use of cable increasing costs.

This points us to that final rings should be all in 4mm, or 4mm on one leg to the clustered heavy current drawing sockets and then 2.5mm for the rest at least, for many reasons. In a normal house/flat I would lean to put as many appliances as possible on a full 4mm ring protected by an AFDD; diversity taken into account of course. A 3kW-ish oven & low current drawing induction hob on a 4mm radial and of course the immersion, if one on premises, on its own 2.5mm radial. Maybe more economical having the immersion on 4mm as final ring and oven/hob will be on 4mm so cable being cheaper all on the same purchased drum. At TLC a 100m drum of 4mm is £147 (£1.47 p/m), with 100m drum of 2.5mm £72 (£0.72 p/m), about twice the price, but £1.03p on a 25m drum. Costs of 4mm could drop in cable costs as only using one final ring in 4mm. Worth thinking about.

I have come across plenty of open rings in domestic settings, but have never once found one where the cables were showing signs of aging, let alone thermal damage, as a result of overload. I'm of the opinion that the sorts of overload that are likely to occur are not great enough to cause actual damage, even when the ring is open, or the load heavily biased to one leg.

It's good to explore these things, as it gives us a better understanding of the circuits we work on, but I don't think 4mm is generally necessary for wiring rings.

 

[mainline]

Deja vu comes to mind with this thread.

 

[Steve-S]

I have come across plenty of open rings in domestic settings, but have never once found one where the cables were showing signs of aging, let alone thermal damage, as a result of overload. I'm of the opinion that the sorts of overload that are likely to occur are not great enough to cause actual damage, even when the ring is open, or the load heavily biased to one leg.

It's good to explore these things, as it gives us a better understanding of the circuits we work on, but I don't think 4mm is generally necessary for wiring rings.

Nice comment. Thanks for your input. It is a valued judgment of course. OK a worst case scenario - like the Christmas dinner scenario in cookers. Wife has the washing on in the kitchen. Tumble dryer constantly drawing 13A, washing machine intermittently cuts in drawing 11A, fridge cutting in and out, TV on in the corner. Her three friends pop in, the 3kW full kettle goes taking a time to heat up, and the 1kW toaster. Dishwasher is also switched on.

The ring can reach the 32A. it will not trip as it will take more than 32A. The kettle and toaster then cut out taking it below 32A.

a) The point is the ring may be on max more often than you might think.

Then if the ring is out of balance by 80-20 one leg will draw 25.6A, which may be over the max rating of the cable taking derrating into account.

Again:
b) The cable on many occasions will be over its limit more times than we might think it would be.

c) The cable insulation would deteriorate quicker than we might think being heated more times than we might think.

My prime point is that if the ring looks like being heavily unbalanced, run 4mm on one leg to the cluster of heavily loaded sockets. Belt and brace and certainly will ensure no, or minimal, insulation breakdown. 4mm easily cope with 25.6A without and adverse effects in 95% plus of situations, taking into account derrating A valued decision of course.

Yes, it does give us a better understanding, and well worth doing the maths and understanding.

 

[Pretty Mouth]

Nice comment. Thanks for your input. It is a valued judgment of course. OK a worst case scenario - like the Christmas dinner scenario in cookers. Wife has the washing on in the kitchen. Tumble dryer constantly drawing 13A, washing machine intermittently cuts in drawing 11A, fridge cutting in and out, TV on in the corner. Her three friends pop in, the 3kW full kettle goes taking a time to heat up, and the 1kW toaster. Dishwasher is also switched on.

The ring can reach the 32A. it will not trip as it will take more than 32A. The kettle and toaster then cut out taking it below 32A.

a) The point is the ring may be on max more often than you might think.

Then if the ring is out of balance by 80-20 one leg will draw 25.6A, which may be over the max rating of the cable taking derrating into account.

Again:
b) The cable on many occasions will be over its limit more times than we might think it would be.

c) The cable insulation would deteriorate quicker than we might think being heated more times than we might think.

My prime point is that if the ring looks like being heavily unbalanced, run 4mm on one leg to the cluster of heavily loaded sockets. Belt and brace and certainly will ensure no, or minimal, insulation breakdown. 4mm easily cope with 25.6A without and adverse effects in 95% plus of situations, taking into account derrating A valued decision of course.

Yes, it does give us a better understanding, and well worth doing the maths and understanding.

I hear what you're saying, but I really think if it was a problem, we'd occasionally come across rings that were deteriorated significantly, or even slightly. I think the margin of error is enough to absorb this sort of thing.

This shows approximate life expectancy of cables for various temperatures, starting at the operating temperature of 70 deg C. Even running at a continuous 115 deg C (that's 45 deg hotter than it should!), it would take about 2 months before PVC cable deteriorated (that's 1460 hours!). I don't know exactly what overload would cause the cable to heat to that temperature, but I would have though it'd need to be significant. In a domestic setting, it seems unlikely to me that overloads such as you describe would be sustained for long enough to cause any real damage.

 

[Steve-S]

I hear what you're saying, but I really think if it was a problem, we'd occasionally come across rings that were deteriorated significantly, or even slightly. I think the margin of error is enough to absorb this sort of thing.

This shows approximate life expectancy of cables for various temperatures, starting at the operating temperature of 70 deg C. Even running at a continuous 115 deg C (that's 45 deg hotter than it should!), it would take about 2 months before PVC cable deteriorated (that's 1460 hours!). I don't know exactly what overload would cause the cable to heat to that temperature, but I would have though it'd need to be significant. In a domestic setting, it seems unlikely to me that overloads such as you describe would be sustained for long enough to cause any real damage.

View attachment 118381

Thanks. Interesting table that says a lot. T&E can take some abuse for sure. Ten years ago I was involved in the renovation of a 1966 house that was super modern at the time. Spiral staircase the lot, like you saw in the Avengers. Built by an architect for himself who lived there alone until he died. It had original brushed steel flat plate sockets. I was amazed they even existed then - must have been a very expensive special order and designer at the time. The place was gas cooking and gas forced air heating, with a 3kW electric immersion for the DHW, the heaviest electrical appliance.

The quality looking wiring passed an insulation test. As much of the old wiring was used as possible as it would be a big messy job getting new cable to the new CU located in an externally accessed cupboard away from the main house. A gas hob and high flow combi was installed heating the new forced air unit with an electrostatic air filter, so the only high current appliance was the 3kW oven. It was built when there was town gas so the gas pipes were 1", nice and big for the new high power natural gas combi.

 

[brianmoooore]

In fifty years, the only cable I've seen damaged by excess current was a 6mm2 earth bond to the mains water pipe on a TNC-S system. The first glimpse I caught of it, under a floorboard in the bathroom, I made some mutterings about plumbers and their blowlamps but when more boards were lifted I could see it was well cooked along its entire length.

 

[Steve-S]

In fifty years, the only cable I've seen damaged by excess current was a 6mm2 earth bond to the mains water pipe on a TNC-S system. The first glimpse I caught of it, under a floorboard in the bathroom, I made some mutterings about plumbers and their blowlamps but when more boards were lifted I could see it was well cooked along its entire length.

Sounds like a Neutral dropped out with all going via the earth cable, even next doors.

 

[brianmoooore]

Sounds like a Neutral dropped out with all going via the earth cable, even next doors.

Only a small village, and only one more property 'down the line', but that's probably happened at sometime in the past.
Insulation on the wire was properly bubbled up and blackened all along, but removed and replaced by a 10mm2 as part of the rewire/extension I was doing at the time.

 

[Steve-S]

Only a small village, and only one more property 'down the line', but that's probably happened at sometime in the past.
Insulation on the wire was properly bubbled up and blackened all along, but removed and replaced by a 10mm2 as part of the rewire/extension I was doing at the time.

John Ward did an excellent demo rig explaining your scenario. Woud have been best to convert to TT earthing in the renovation.

View: https://www.youtube.com/watch?v=fen8ekrhlBI&t=1s

 

[Pretty Mouth]

By chance this popped up on youtube earlier, it shows T+E overloaded to destruction. The experiment is a little flawed IMO, because he doesn't really allow enough time for the smaller overloads to reach their peak temperature, but it still may be of interest.

View: https://www.youtube.com/watch?v=IF2UvUZoO2E

 

[PS Electrics]

By chance this popped up on youtube earlier, it shows T+E overloaded to destruction. The experiment is a little flawed IMO, because he doesn't really allow enough time for the smaller overloads to reach their peak temperature, but it still may be of interest.

View: https://www.youtube.com/watch?v=IF2UvUZoO2E

Popped up in mine as well, looks like the algorithm is finding us!

 

[brianmoooore]

I have an old Pichill 180A stick arc welder that gets dragged out occasionally for some heavy duty welding. On a few occasions, when it's been out and I've been bored, I've connected the odd metre or two of T&E or singles between its clamps just to see what happens at various currents.
General conclusion is that it'll take considerably more current than you might think before damage occurs.

 

[KungFuTurkeyLeg]

Why not rebalance the ring by extending it in one of the cavities? It's an old ideology but in theory works. Calculate the length to the two sockets feeding kettle and dryer, for example, by splitting the ring. Then calculate the distance from the other side of the split ring socket back to the CU. L1 = 10m and L2 = 15m, add a 5m figure of 8 onto L2 and reconnect the ring. 15m/15m each side of the ring to the heaviest loads

Diversity wipes out the above though. But something like this I would look to do at design stage and make it a none issue

 

[Steve-S]

Why not rebalance the ring by extending it in one of the cavities? It's an old ideology but in theory works. Calculate the length to the two sockets feeding kettle and dryer, for example, by splitting the ring. Then calculate the distance from the other side of the split ring socket back to the CU. L1 = 10m and L2 = 15m, add a 5m figure of 8 onto L2 and reconnect the ring. 15m/15m each side of the ring to the heaviest loads

Diversity wipes out the above though. But something like this I would look to do at design stage and make it a none issue

Thx, but:
"L1 = 10m and L2 = 15m, add a 5m figure of 8 onto L2 and reconnect the ring. 15m/15m each side of the ring to the heaviest loads"

Did you mean L1 not L2?

 

[mainline]

Thx, but:
"L1 = 10m and L2 = 15m, add a 5m figure of 8 onto L2 and reconnect the ring. 15m/15m each side of the ring to the heaviest loads"

Did you mean L1 not L2?

I think he means Leg 1 and Leg 2.

 

[KungFuTurkeyLeg]

Thx, but:
"L1 = 10m and L2 = 15m, add a 5m figure of 8 onto L2 and reconnect the ring. 15m/15m each side of the ring to the heaviest loads"

Did you mean L1 not L2?

Yep! Edit button was disabled by the time I seen it. Hopefully the 15m/15m clarified what I intended