Interested in your thoughts....

[Deleted member 9648]

IMO it relates more commonly to the reduction in CSA of a pendant wired in 0.5mm flex from a 1mm or 1.5mm lighting circuit, but either way in this situation there should be a protective device at the reduction in CSA where the ring 'lollypops' off, making the SWA a submain. The ring would then begin at this point, in line with convention.

What would you suggest as a protective device at the point where the radial becomes a ring?....given that there is a 32a RCBO at the origin,in order to provide discrimination a 20a device would be required at the point of change according to your view...note change,not reduction..as both the SWA and ring meet the requirements for a 32a OCPD the change surely cant be classed as a reduction?

 

[Engineer54]

IMO it relates more commonly to the reduction in CSA of a pendant wired in 0.5mm flex from a 1mm or 1.5mm lighting circuit, but either way in this situation there should be a protective device at the reduction in CSA where the ring 'lollypops' off, making the SWA a submain. The ring would then begin at this point, in line with convention.

In simple terms now ....Rubbish!! Lollipop rings have been around for years now. Providing protective measures are fulfilled along with any other circuit parameters then they are electrically sound and will comply....

 

[Adam W]

What would you suggest as a protective device at the point where the radial becomes a ring?....given that there is a 32a RCBO at the origin,in order to provide discrimination a 20a device would be required at the point of change according to your view...note change,not reduction..as both the SWA and ring meet the requirements for a 32a OCPD the change surely cant be classed as a reduction?

If there is a protective device where the SWA joins the ring the protective device at the origin could be something other than a 32A RCBO. Alternatively maybe a different installation method could be used to make the circuit an ordinary ring; I don't know, I don't like to ask.

 

[Adam W]

In simple terms now ....Rubbish!! Lollipop rings have been around for years now. Providing protective measures are fulfilled along with any other circuit parameters then they are electrically sound and will comply....

Well do that then. I don't like the idea of a lollypop circuit, but then it's not me doing the job.

 

[Engineer54]

If you bothered to read the posts i've made on this thread, you would have seen from my comment's that i don't particually like them either!! But that does not get away from the fact, ...that there is nothing electrically wrong with them!!!

 

[Engineer54]

If there is a protective device where the SWA joins the ring the protective device at the origin could be something other than a 32A RCBO. Alternatively maybe a different installation method could be used to make the circuit an ordinary ring; I don't know, I don't like to ask.

You don't have to Ask, ...that question has been answered in my Post #25, that i believe i directed you too previously...

 

[Guest112]

#long sigh, handbag down E54 its over

 

[Adam W]

You don't have to Ask, ...that question has been answered in my Post #25, that i believe i directed you too previously...

I read your post #25 and it didn't explain why you 'have to' install the circuit like this, not that I should bother reading your posts when you can't even be bothered to explain your ambiguous initialisms.

Like I've already said you can either install a lollypop circuit or not.

 

[Engineer54]

I read your post #25 and it didn't explain why you 'have to' install the circuit like this,
Like I've already said you can either install a lollypop circuit or not.

QUOTE from post #25 ....The submittal was back on my desk yesterday morning, now showing 2 X 3core 4mm SWA to the JB box's and 2 X 3 core 4mm building cables forming the Final Ring Circuits,

Does this sound like a lollipop ring to you then?? The rings have now been approved in a conventional configuration, FFS!! :6:

 

[Chr!s]

The Lollipop Circuit

In my design ill assume that at the far end of the circuit there is a 20 amp load and an additional 12 evenly distributed around the circuit, average current = 32 + 20/2 = 26 amps.Providing load current in any part does not exceed 26amps we may use an Iz of the below.

Iz Equal > 26 amp, 6mm, 2.5 so both are o.k

Volt drop = Distribution Circuit 10 meters 6mm, Ring/Parallel circuit 60 meters


Radial = 2.336 volts Ring equals = 7.02 volts = 9.356 volts so less tan the 11.5

Fault Protection Maz Zs(32 Amp type B) = 1.44 Ohms Ze = .35 Ohms(TNC-S) 100 amp 1361 type II


Distribution Circuit = .13 Ohms Ring = .35 Ohms = ZS = .83 So comply's

Fault current Protection Front end using adiabatic and energy let throughs Minimum size = . 38mm

far end minimum size .21mm so comply's

Short circuit Front end .38mm Far end = .30mm so comply's32 Type b 60898, fusing factor 1.45 = Must trip within 1 hour at 46.4 amps

If i place a 46.4 load between the two legs at the mid point of a ring the load will be split between the two legs.

So we know it will trip within 1 hour at that load and the split load will equal 23.2 amps per leg, now 2.5 is 27 amps.

Is the cable protected yes.

The key is even distribution of load.

Now common sense tells us that if i place some 6mm in front of this ring it not going to have a major impact on the current distribution of the circuit.

Omit overload Protection at JB Using 433.3.1

Utilizing Appendix ten and using kirchoff's law to evaluate the load in each section, it can be seen that the cable is protected.

 

[malcolmsanford]

^^^^^^^^^^^^^^^^^^^ blow me Chr!s think there will be some cut and paste of that for lads wanting to do design .....nice one mate

 

[electromonkey]

The Lollipop Circuit

In my design ill assume that at the far end of the circuit there is a 20 amp load and an additional 12 evenly distributed around the circuit, average current = 32 + 20/2 = 26 amps.Providing load current in any part does not exceed 26amps we may use an Iz of the below.

Iz Equal > 26 amp, 6mm, 2.5 so both are o.k

Volt drop = Distribution Circuit 10 meters 6mm, Ring/Parallel circuit 60 meters


Radial = 2.336 volts Ring equals = 7.02 volts = 9.356 volts so less tan the 11.5

Fault Protection Maz Zs(32 Amp type B) = 1.44 Ohms Ze = .35 Ohms(TNC-S) 100 amp 1361 type II


Distribution Circuit = .13 Ohms Ring = .35 Ohms = ZS = .83 So comply's

Fault current Protection Front end using adiabatic and energy let throughs Minimum size = . 38mm

far end minimum size .21mm so comply's

Short circuit Front end .38mm Far end = .30mm so comply's32 Type b 60898, fusing factor 1.45 = Must trip within 1 hour at 46.4 amps

If i place a 46.4 load between the two legs at the mid point of a ring the load will be split between the two legs.

So we know it will trip within 1 hour at that load and the split load will equal 23.2 amps per leg, now 2.5 is 27 amps.

Is the cable protected yes.

The key is even distribution of load.

Now common sense tells us that if i place some 6mm in front of this ring it not going to have a major impact on the current distribution of the circuit.

Omit overload Protection at JB Using 433.3.1

Utilizing Appendix ten and using kirchoff's law to evaluate the load in each section, it can be seen that the cable is protected.

Ahhhh

I was just about to write that!

Oh well, maybe next time.

 

[Guest112]

one idea would be to use a multicored armoured think theres a 7 core 4mm so one spare but core connect ends at db like a ring and then to the jb keeping it a ring from the db to avoid confusion over the lollypop rubbish

 

[Adam]

434.2.1
"The part of the conductor between the point of reduction of CSA or other change and the position of the protective device shall... ... not exceed 3m in length..."

Does that help?

ie are you fusing it down after the SWA, or could you just use, say, a 4mm radial throughout?

IMO, this regulation is often encountered with busbar systems.

Eg: you have a 100+ amp busbar and supplying a small electrical item. You would take a 6mm2 cable from the busbar to a Fused Switch (for example), rated at 32 amps. This 6mm2 cable should be less than 3m as per mentioned regulation, as it is not suitable for 100 amps.



With regards to Hybrid Ring Final Circuits (lollipop Circuits)! I see no issue with them and would install in certain circumstances.

Eg: computer circuits in Schools / Colleges. Ther is often a requirement of local isolation of sockets in Dado Trunking within IT suites. This is often achieved with 32A DP switches mounted in trunking, with load as a ring for socket outlets.