Bas, any chance of saving me looking through the whole document by telling me where it says this? Somewhere in part G, I guess. No catch - seriously interested.
SWA, sockets, and freedom from RCDs
- Thread starter Hibbo
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Bas, any chance of saving me looking through the whole document by telling me where it says this? Somewhere in part G, I guess. No catch - seriously interested.
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IIRC, up to the 12th Ed, phased out in 1955.
P
Paul_C
Double-pole fusing was permitted under the 12th edition, but did it really permit single-pole fusing in neutral only? Unfortunately I don't have a copy of anything prior to the 13th edition.
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You just new this thread was going to run to several pages from the very first post.......
Happy New Year all!
Happy New Year all!
P
Paul_C
On the building regulations and notification issue, surely only the seriously deluded (and government bureaucrats - but they're merely a subset of the deluded) believe that all legally notifiable work is actually notified?
For DIY jobs which aren't even visible from outside the house, how many people who are quite capable of carrying them out properly are going to throw money at their local council rather than just get on with it? I'm certainly in that group, and would never even consider paying the local tinpot dictators £100, £200 or even more to do a simple job in my own house where the chances of my "crime" being discovered within the short statute of limitations are almost nil.
Getting back to the original problem, however, if it were me I wouldn't be worrying about the ridiculously over-zealous RCD requirements of the 17th edition and would just install the T&E without RCD protection if I wanted a non-RCD outlet. And I can't think why I would need it, but if I were completing an installation certificate for myself, I would note it as a departure.
However, if you want to argue the point about departures being only for non-compliance with regulations where such non-compliance offers a similar level of protection (however that's defined), how about this?
Buried SWA is considered acceptable without RCD protection. We all know that SWA isn't going to stop a nail or a drill, just make sure that said nail or drill is in contact with the earthed armor before it has a chance to reach a live conductor inside.
So what if you were to fit steel capping over T&E and securely earth that capping with a pigtail at the backbox of the socket? Would that not give the same effective (non-)protection from nails, screws, or drills as SWA?
For DIY jobs which aren't even visible from outside the house, how many people who are quite capable of carrying them out properly are going to throw money at their local council rather than just get on with it? I'm certainly in that group, and would never even consider paying the local tinpot dictators £100, £200 or even more to do a simple job in my own house where the chances of my "crime" being discovered within the short statute of limitations are almost nil.
Getting back to the original problem, however, if it were me I wouldn't be worrying about the ridiculously over-zealous RCD requirements of the 17th edition and would just install the T&E without RCD protection if I wanted a non-RCD outlet. And I can't think why I would need it, but if I were completing an installation certificate for myself, I would note it as a departure.
However, if you want to argue the point about departures being only for non-compliance with regulations where such non-compliance offers a similar level of protection (however that's defined), how about this?
Buried SWA is considered acceptable without RCD protection. We all know that SWA isn't going to stop a nail or a drill, just make sure that said nail or drill is in contact with the earthed armor before it has a chance to reach a live conductor inside.
So what if you were to fit steel capping over T&E and securely earth that capping with a pigtail at the backbox of the socket? Would that not give the same effective (non-)protection from nails, screws, or drills as SWA?
Only if the capping is suitable for a cpc.
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I was also thinking along similar lines, I have access to tons of flexshield-type braided cable at work, and as you say a nail going through that would hit the earthed braid before it hit any conductor.
I know that flexshield was acceptable for running outside of safe zones under the 16th, but not in the 17th. Would it be considered an acceptable 'departure' to use flexshield for a non-RCD run?
Using flexishield would aid compliance with 522.6.6 (i).
30mA RCD protection is not then required for the installed cable.
You also have the freedom to run it where you like though you want kicking in the balls if you do!
30mA RCD protection is not then required for the installed cable.
You also have the freedom to run it where you like though you want kicking in the balls if you do!
I'd have thought so. Thanks Col, I thought I was going mad.
P
Paul_C
So that contains the same sort of vague language as the equivalent section of Part P. I don't doubt that my interpretation of that last phrase will be rather different from the LABC's interpretation.
Hibbo said:
I don't see any logical reason why it should not be as acceptable as SWA in this application. It will do exactly the same job in the event of being pierced by a nail or drill.
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I see many references to BS 8436 cables (Flexshield and similar) suggesting that it can be used to meet [522.6.5 (ii)], [522.6.6 (i)] and [522.6.8 (i)].
This is only correct if an assessment has been made of fault levels along the run of the circuit. Note that the fault level close to the main intake will be much higher than the level at the end of a final circuit - do you know where the nail will be driven in
.
BS 7671 requires that you take account of the 'conditions of use' imposed by manufacturers and equipment standards.
From BS 8436
The selection of a protective device should be made in the normal way in accordance with BS 7671, taking into account the nail penetration test current stated for the cable and the maximum let-through energy allowed.
The allowed maximum let-through energy (I2t) for 1.0 mm2 and 1.5 mm2 cable is 42 000 A2s, and for 2.5 mm2 cable is 60 000 A2s.
It is essential that any device selected does not require a higher current to operate than that stated for the nail penetration test, and does not have a higher let-through energy than stated above.
The designer of the circuit may consider additionally having supplementary protection by a residual current device in accordance with BS 7671:2001, 412-06-02ii).
The selection of a protective device should be made in the normal way in accordance with BS 7671, taking into account the nail penetration test current stated for the cable and the maximum let-through energy allowed.
The allowed maximum let-through energy (I2t) for 1.0 mm2 and 1.5 mm2 cable is 42 000 A2s, and for 2.5 mm2 cable is 60 000 A2s.
It is essential that any device selected does not require a higher current to operate than that stated for the nail penetration test, and does not have a higher let-through energy than stated above.
The designer of the circuit may consider additionally having supplementary protection by a residual current device in accordance with BS 7671:2001, 412-06-02ii).
The 1 s test current of 80 A for the 1.0 mm2 cable corresponds to a current that will operate up to a 16 A Type B circuit breaker conforming to BS EN 60898 and RCBOs conforming to BS EN 61009-1, as stated in BS 7671:2001, Appendix 3, Figure 3.4 in 0.1 s for a radial circuit.
The 1 s test current of 100 A for the 1.5 mm2 cable corresponds to a current that will operate up to a 20 A Type B circuit breaker conforming to BS EN 60898 and RCBOs conforming to BS EN 61009-1, as stated in BS 7671:2001, Appendix 3, Figure 3.4 in 0.1 s for a radial circuit.
The 1 s test current of 160 A for the 2.5 mm2 cable corresponds to a current that will operate up to a 32 A Type B circuit breaker conforming to BS EN 60898 and RCBOs conforming to BS EN 61009-1, as stated in BS 7671:2001, Appendix 3, Figure 3.4 in 0.1 s for a ring circuit.
The 1 s test current of 80 A for the 1.0 mm2 cable corresponds to a current that will operate up to a 16 A Type B circuit breaker conforming to BS EN 60898 and RCBOs conforming to BS EN 61009-1, as stated in BS 7671:2001, Appendix 3, Figure 3.4 in 0.1 s for a radial circuit.
The 1 s test current of 100 A for the 1.5 mm2 cable corresponds to a current that will operate up to a 20 A Type B circuit breaker conforming to BS EN 60898 and RCBOs conforming to BS EN 61009-1, as stated in BS 7671:2001, Appendix 3, Figure 3.4 in 0.1 s for a radial circuit.
The 1 s test current of 160 A for the 2.5 mm2 cable corresponds to a current that will operate up to a 32 A Type B circuit breaker conforming to BS EN 60898 and RCBOs conforming to BS EN 61009-1, as stated in BS 7671:2001, Appendix 3, Figure 3.4 in 0.1 s for a ring circuit.
The let through energies stated can be exceeded by some protective devices found in domestic dwellings. A check should be made against the standard for the device or with the manufacturer. They would need to know the fault level at the intake to give accurate advice.
If you are doing new works, using equipment which you know limits the let through energy to a safe value - then BS 8436 cables may well be a satisfactory solution - but if this is not the case you should carry out an assessment.
This is only correct if an assessment has been made of fault levels along the run of the circuit. Note that the fault level close to the main intake will be much higher than the level at the end of a final circuit - do you know where the nail will be driven in
. BS 7671 requires that you take account of the 'conditions of use' imposed by manufacturers and equipment standards.
From BS 8436
The selection of a protective device should be made in the normal way in accordance with BS 7671, taking into account the nail penetration test current stated for the cable and the maximum let-through energy allowed.
The allowed maximum let-through energy (I2t) for 1.0 mm2 and 1.5 mm2 cable is 42 000 A2s, and for 2.5 mm2 cable is 60 000 A2s.
It is essential that any device selected does not require a higher current to operate than that stated for the nail penetration test, and does not have a higher let-through energy than stated above.
The designer of the circuit may consider additionally having supplementary protection by a residual current device in accordance with BS 7671:2001, 412-06-02ii).
The selection of a protective device should be made in the normal way in accordance with BS 7671, taking into account the nail penetration test current stated for the cable and the maximum let-through energy allowed.
The allowed maximum let-through energy (I2t) for 1.0 mm2 and 1.5 mm2 cable is 42 000 A2s, and for 2.5 mm2 cable is 60 000 A2s.
It is essential that any device selected does not require a higher current to operate than that stated for the nail penetration test, and does not have a higher let-through energy than stated above.
The designer of the circuit may consider additionally having supplementary protection by a residual current device in accordance with BS 7671:2001, 412-06-02ii).
The 1 s test current of 80 A for the 1.0 mm2 cable corresponds to a current that will operate up to a 16 A Type B circuit breaker conforming to BS EN 60898 and RCBOs conforming to BS EN 61009-1, as stated in BS 7671:2001, Appendix 3, Figure 3.4 in 0.1 s for a radial circuit.
The 1 s test current of 100 A for the 1.5 mm2 cable corresponds to a current that will operate up to a 20 A Type B circuit breaker conforming to BS EN 60898 and RCBOs conforming to BS EN 61009-1, as stated in BS 7671:2001, Appendix 3, Figure 3.4 in 0.1 s for a radial circuit.
The 1 s test current of 160 A for the 2.5 mm2 cable corresponds to a current that will operate up to a 32 A Type B circuit breaker conforming to BS EN 60898 and RCBOs conforming to BS EN 61009-1, as stated in BS 7671:2001, Appendix 3, Figure 3.4 in 0.1 s for a ring circuit.
The 1 s test current of 80 A for the 1.0 mm2 cable corresponds to a current that will operate up to a 16 A Type B circuit breaker conforming to BS EN 60898 and RCBOs conforming to BS EN 61009-1, as stated in BS 7671:2001, Appendix 3, Figure 3.4 in 0.1 s for a radial circuit.
The 1 s test current of 100 A for the 1.5 mm2 cable corresponds to a current that will operate up to a 20 A Type B circuit breaker conforming to BS EN 60898 and RCBOs conforming to BS EN 61009-1, as stated in BS 7671:2001, Appendix 3, Figure 3.4 in 0.1 s for a radial circuit.
The 1 s test current of 160 A for the 2.5 mm2 cable corresponds to a current that will operate up to a 32 A Type B circuit breaker conforming to BS EN 60898 and RCBOs conforming to BS EN 61009-1, as stated in BS 7671:2001, Appendix 3, Figure 3.4 in 0.1 s for a ring circuit.
The let through energies stated can be exceeded by some protective devices found in domestic dwellings. A check should be made against the standard for the device or with the manufacturer. They would need to know the fault level at the intake to give accurate advice.
If you are doing new works, using equipment which you know limits the let through energy to a safe value - then BS 8436 cables may well be a satisfactory solution - but if this is not the case you should carry out an assessment.
They could be, and it would certainly help, but then you go into the realm of the other posts with respect to informing people of the uses of nearly every other commodity. So I won’t suggest they do that.
It's certainly a bit cheeky for retailers to sell windows without further information, but like I say, to a DIYer they can have many other uses around their property.
Consumer units are a special case in point. To a DIYer carrying out home improvements, they only ever have one use, and installing for that use without notification under a not-very-well-known set of regulations will always cause them to break the law, no matter where on their property they install it.
Exactly, if people are certain to be flouting the law then they need to be made aware of it. Most people who drive with no insurance know they are doing so illegally. Most who buy a CU from a home improvements chain won't.
If a law was passed whereby the fitment of a 13A plug to an appliance in your own home was made illegal unless you sent away a cheque to your local authority then until that law became widely known then you'd expect Currys etc to carry that warning when buying an appliance with none fitted.
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