I'm not trying to be funny - I'd love to know where that quote is from, and the context, but so far all I've got to go on are the words in the regs and the OSG, which say that 4D5A is for flat twin/earth, and the words in the Wiring Matters article on Amendment 1 which explicitly say that 4D2A is based on round cables....
I'm not trying to be funny Please keep reading the pdf ...1st few paragraphs The reasons for the table 4D5A and when it should be used instead of 4D2A should become clear. You will see that 4D2A is mentioned in connection with 2.5mm T&E and that the issue was with thermal insulated walls... the issues also arose because the figures were based upon results using round cables... thus 4D2A is used for T&E Thats figures based upon... not for.
Assuming that we are talking about the same PDF document, what that says is that the figures in 4D2A were based on the performance of round cables, and that the Electrical Research Association were asked to measure the rating of the standard UK flat twin with earth insulated and sheathed cables, and that they did so, and got different results and so a new table, 4D5A, was created to provide the results for standard UK flat twin with earth insulated and sheathed cables...
All of them. 1) Someone spots that the old ratings, in 4D2A, meant that in extremis 2.5mm² would not be OK for a ring final. 2) "Oo err, we'd better look into this properly. ERA - we understand that 4D2A is based on the performance of round cables, will you please run some tests using UK flat twin & earth cables?" 3) "OK, IEE, we have done those tests, and we get different results for UK flat twin & earth cables. Here they are." 4) "Thank you, ERA. We will publish these new figures for the ratings of UK flat twin & earth cables in a new table, 4D5A, as part of an amendment to the Wiring Regulations.
Where is It should however be noted that for PVC sheathed flat cables two current rating tables are given 4D2A and 4D5A. > 4D5A should be used where Reference Method 1 is applicable, AND where these cables are in contact with thermal insulation on one side (Installation Methods 6 and 15). 4D2A should be used for other applications including where Reference methods 3 and 11 are applicable. from?
1) Someone spots that the old ratings, in 4D2A, meant that in extremis 2.5mm² would not be OK for a ring final. RM are the only circuits you dont need to design! So dont worry A1 A2 & A3 circuits Ant
Ok BAS ... another day lets try another method The original poster stated how the cable was run to the shower.. What reference method do you think it is ? Can you find it on the table you wanted to use ?
"Cable already fitted is 6mm2, loosley fitted in brickwork". "Loosely fitted in brickwork" is a bit like being embedded and/or a bit like being clipped to the surface of brickwork. Table 4A1. <u>Open and clipped direct</u>. Installation method 1. Sheathed cables clipped direct to or lying on a non-metallic surface. Appropriate Reference Method for determining current carrying capacity: Method 1. <u>Cables embedded directly in building materials</u>. Installation method 2: Sheathed cables embedded directly in masonry, brickwork, concrete, plaster or the like (other than thermally insulating materials). Appropriate Reference Method for determining current carrying capacity: Method 1. So "loosely fitted in brickwork" would seem to be Reference Method 1. Table 4D5A. Column 4. Reference Method 1. 6mm² 47A.
In general... I'd of more prefered the example picture of voids in Installation method 16 giving ref method 4.
Or even ref method 3 if the greater % of the cable run complys... Neither of which are available in 4D5A If in doubt.. use 4D2A (look at the ratings and see why)
Re: Shower Cable - to be 6mm2? Posted: Jan 12, 2007 4:58 PM Reply I was referring to this table Standard Shower Rating Watts (kW) Maximum load from the supply A Maximum size of Protective device Recommended Minimum Cable Size to be Used Recommended Protective Device 6000 (6kW) 26 32A 6mm2 RCBO 6500 (6.5kW) 28.2 32A 6mm2 RCBO 7000 (7kW) 30.4 32A 6mm2 RCBO 7500 (7.5kW) 32.6 40A 10mm2 RCBO 8000 (8kW) 34.7 40A 10mm2 RCBO 8500 (8.5kW) 36.95 40A 10mm2 RCBO 9000 (9kW) 39.13 40A 10mm2 RCBO 9500 (9.5kW) 41.3 45A 10mm2 RCBO 10,000 (10kW) 43.47 45A 10mm2 RCBO 10,500 (10.5kW) 45.65 50A 16mm2 RCBO 11,000 (11.0kW) 47.82 50A 16mm2 All data in this table has been compiled with reference to BS7671: 2001. The IEE Wiring Regulat Cable Data taken from Table 4D2A. Page 222. Why does'nt the 11.0 KW need a RCBO but all the others do ? I would say because you can’t buy an 11kw Shower? On the market now is a 10.8kw
Actually, it doesn't need an RCBO, so long as the Zs allows a disconnection time of 0.4s, which most radials for a shower will do. Who gave you that information? Certainly not BS7671.
The makers of the showers sometimes mention that a rcd is needed or something like that.. IMHO its a cop out for them being held liable if the naked doris gets fried in the shower
RCD/no RCD ? Which is safer(for the person in the shower)with certain eventualities considered ? Mr. HandyAndy - really
Why would you fit an RCD? Is that question specifically to me ? Er, for one, in case the water inadvertently made a live cable pass electricity to the shower fitment, and possibly, me. I'd like to know that if I were an earth path, that I would not be an earth path for very long, without dying. Mr. HandyAndy - really
Forums
Facebook
Twitter
You Tube
Instagram
Shop