Discuss looking through previous certificate and have a question about disconnection time. in the Security Alarms, Door Entry and CCTV (Public) area at ElectriciansForums.net

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On a domestic inspection and testing certificate or conditional reports, I always put maximum disconnection time permitted by BS7671 as 0.4 sec. I've been given a testing job for an HMO property and on the previous conditional report, the maximum disconnection time of 0.4 sec is only given for the sockets. Everything else is 5 seconds, for example, lights, shower, and immersion heater. I thought this is wrong but the person who carried out these tests are experienced, not saying they are right. But they could be, as they are busy in testing jobs. Can anybody give me any insight please.
 
I have a feeling that's been tightened up, but I'm pretty sure the 0.4 applied to portable equipment likely to be held and not to fixed equipment. When was the previous report done?
 
0.4s is the disconnection time for a final circuit <=32A @230V on a TN earthed installation.
So it is possible that the shower, if a 40A+ radial, could have a 5s disconnection time.
Other than that only distribution circuits should have a 5s disconnection time.
Lights and immersion heaters will not be distribution circuits and are not going to be over 32A so I would expect that they should be 0.4s.
 
0.4s is the disconnection time for a final circuit <=32A @230V on a TN earthed installation.
So it is possible that the shower, if a 40A+ radial, could have a 5s disconnection time.
Other than that only distribution circuits should have a 5s disconnection time.
Lights and immersion heaters will not be distribution circuits and are not going to be over 32A so I would expect that they should be 0.4s.
Is it 5 seconds because anything over 32A is not going to be handheld.
 
Yes it was tightened up 10 years ago exactly, so it depends when the circuits were designed.
It was purely related to hand held equipment, now as above it's related to the size of the protective device it whether it's a distribution circuit.
 
Last inspection
So basically you'll need either the installation cert or guess which edition it was designed to.
Perhaps the previous guy knew some history that's not obvious now, but given that documentary evidence, unless you have other reason to think it was later, i would just follow that and inspect/test according to that. No one can expect you to have a psychic power, you can only report based on what you see.
 
So basically you'll need either the installation cert or guess which edition it was designed to.
Perhaps the previous guy knew some history that's not obvious now, but given that documentary evidence, unless you have other reason to think it was later, i would just follow that and inspect/test according to that. No one can expect you to have a psychic power, you can only report based on what you see.
Maybe he just never bothered buying the newer Reg books, or if he did, never bothered reading them.
 
120V to 230V d.c. used to be 5s for TN installations.
I have checked and that is what the table states; It is that sort of change that I tend to miss, admittedly it will possibly never come up but can be annoying. I know I missed something similar on another reg at the last change.
Then again it could be the first of the errors:anguished:

re the OP if the inspection was being carried out in June 2015 then the regulations to which he is inspecting are the 17th edition so there is no reason to have written a 5s disconnection time in the report, it would only be a comment that the installation was designed to different disconnection times.
 
I have checked and that is what the table states; It is that sort of change that I tend to miss, admittedly it will possibly never come up but can be annoying. I know I missed something similar on another reg at the last change.
Then again it could be the first of the errors:anguished:

re the OP if the inspection was being carried out in June 2015 then the regulations to which he is inspecting are the 17th edition so there is no reason to have written a 5s disconnection time in the report, it would only be a comment that the installation was designed to different disconnection times.

This is what I was thinking, but I had to ask as this company has more experience than me, so I guessed they had there reasons. The testing results has to meet the latest Regs. The test papers are to 17th edition. I had to ask as I know I could be also wrong as I have lack of experience in testing.
 
Was just looking through 18th edition changes online

The maximum disconnection times stated in Table 41.1 now apply for final circuits up to 63 A with one or more socket-outlets and 32 A for final circuits supplying only fixed connected current-using equipment (Regulation 411.3.2.2).

I haven't got the 18th edition yet, did this take effect within the new regs?
 
Was just looking through 18th edition changes online

The maximum disconnection times stated in Table 41.1 now apply for final circuits up to 63 A with one or more socket-outlets and 32 A for final circuits supplying only fixed connected current-using equipment (Regulation 411.3.2.2).

I haven't got the 18th edition yet, did this take effect within the new regs?
Yes the final circuits with sockets has been increased from 32A to 63A minimum with effect from the 18th Edition.
 
so that's virtually everything os 0.4secs.( except for distribution circuits). only considering domestic and light industrial here, not the heavy stuff.
 

Reply to looking through previous certificate and have a question about disconnection time. in the Security Alarms, Door Entry and CCTV (Public) area at ElectriciansForums.net

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