Something's wrong here - the switches currently being sold by TLC (per pics on page 2) are being attributed to Klockner Moeller - see here....
Kind Regards, John
Changeover Switch
- Thread starter russellsmiler
- Start date
Kind Regards, John
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OK, suppose we just have a "normal" situation of one supply from a house to a shed, would you write "the incomer to the shed needs to have an isolator in the shed where it can be seen by anyone who is working on the switch. If the isolator is in the house it could be turned on by someone unware that someone is working on the main switch in the shed." ?
No, I don't think we would. In the case of a normal single supply to a CU, anyone working on a circuit that can't be fully isolated and locked off by the main switch in teh CU would go back up a level and lock off the upstream supply. Where there are two supplies, that just means locking off two supplies - though there is an implicit assumption there that someone has two lockoffs to hand.
I see no safety issue here that doesn't apply to ANY circuit - if you are going to work on/in <something> then you need to isolate and lockoff all supplies to it. Don't forget that in industrial settings, it's not that uncommon to have multiple supplies into some types of equipment.
Essentially true, but there is a pretty unusual practical issue here - that one of the two points of upstream isolation is in someone else's property, and therefore may not be accessible when needed (e.g. "in an emergency"). So, on the basis of that very unusual situation, I think there probably would (unusually) be a case for local isolators on both incoming supplies to the outbuilding.
Kind Regards, John
Surely 2 commando sockets as mentioned on the other thread is much less complicated, avoids all these issues and is going to be cheaper than a changeover switch too.
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I think most people probably agree with that, but it does not necessarily avoid all of the issues. For example, it probably requires that the outbuilding is TTd - I suspect that a plug/socket in the earthing (and bonding, if required) path would not be regarded as acceptable. Also, as BAS pointed out, unless supplies were isolated (well, 'switched off') at the house end, a widow-maker would enable pilfering of the neighbour's electricity!
One worrying aspect of any method is that it involves electricity entering a building for which a means of always-accessible upstream isolation does not exist. Risks are very small, but I would personally like to think that I always had access to a means of disconnection of an electricity supply (without having to do any breaking and entering!).
Kind Regards, John
feel like ive started a reasonable debate!!
Just to add
Yes, we have bought the said changeover switch as previously shown in picture form, Agree its old, possibly had a chequered history.
so as well as visual inspection, possible mock up trial of use (possible using 12 volt just to see if switch acts as according to position etc), and general feel for wobbly bits. how and who decides its serviceable and completely safe to use.
Also planning to sign above the switch with explantion of installation and warning that Both property CU must be isolated before work on!
Just to add
Yes, we have bought the said changeover switch as previously shown in picture form, Agree its old, possibly had a chequered history.
so as well as visual inspection, possible mock up trial of use (possible using 12 volt just to see if switch acts as according to position etc), and general feel for wobbly bits. how and who decides its serviceable and completely safe to use.
Also planning to sign above the switch with explantion of installation and warning that Both property CU must be isolated before work on!
How closely will you inspect the switch contacts?
Which will tell you absolutely nothing about how it will perform at 230V, and passing 32A.
And have you found out yet what the Iu (rated uninterrupted current) is for the switch?
How about the person qualified to sign the EIC for it?
Who will that be, BTW?
Not good enough.
Amongst other sources of information i believe if i slowly and methodically set about determining the switches servicaability, both by way of internet, and hopefully this forum
http://www.tpub.com/neets/book3/9f.htm
Still Not sure why a sign stating to isolate both house C/Us is classed as not enough?? When it comes to anyone working on switch, surely the only person who would work on this would be an electrician of some sort, and assuming he/she knows that you can get a fair belt from 240V they would determine the sources of power to the switches, I dont see how a bit of assisstance by way of sign wont help, I could write a full blown O &M Manual for my property, and of course my neighbour!! (Ironically are in the middle of doing one for a building i am handing over in Deeside,which when testing the electric installation yesterday had no end of faults, ).
Obviously if someone who just wants to prod about and as no electrical knowledge and for no apparent reason they should expect a belt, same as they would if they worked the live side of my cooker socket.
http://www.tpub.com/neets/book3/9f.htm
Still Not sure why a sign stating to isolate both house C/Us is classed as not enough?? When it comes to anyone working on switch, surely the only person who would work on this would be an electrician of some sort, and assuming he/she knows that you can get a fair belt from 240V they would determine the sources of power to the switches, I dont see how a bit of assisstance by way of sign wont help, I could write a full blown O &M Manual for my property, and of course my neighbour!! (Ironically are in the middle of doing one for a building i am handing over in Deeside,which when testing the electric installation yesterday had no end of faults, ).
Obviously if someone who just wants to prod about and as no electrical knowledge and for no apparent reason they should expect a belt, same as they would if they worked the live side of my cooker socket.
Russell
Please listen and act on the advice you are being given.
You also have to consider that at some time in the future the supplies to the houses may be upgraded and then no longer are they on the same phase. That would make the low cost single switch change over unit a very dangerous item, is it rated at 415 volts. Memories fade and the upgrade may happen without anyone remembering the change over was designed (?) for use on two supplies from the same phase.
How will you test the switch for inter connect insulation resistance. It may pass all tests at 12 volts and still go short circuit at 230 volts. Heat damaged insulation can resist 12 volts but not 230 volts.
Signs inform. they do NOT prevent.
Some years ago a colleague and I came close to serious micro-wave burns when a ship's captain ignored signs and turned the RADAR from standby to run. We had removed the waveguide ( the pipe that takes the microwave energy up to aerial ) to acess the internals to test and measure the scan drives and the magnatron was pointing straight at us.
His "excuse" was that the maker's label said " Put on standby for 5 minutes before running" which contradicted our safety sign of "Leave on Standy DO NOT RUN"
Please listen and act on the advice you are being given.
You also have to consider that at some time in the future the supplies to the houses may be upgraded and then no longer are they on the same phase. That would make the low cost single switch change over unit a very dangerous item, is it rated at 415 volts. Memories fade and the upgrade may happen without anyone remembering the change over was designed (?) for use on two supplies from the same phase.
How will you test the switch for inter connect insulation resistance. It may pass all tests at 12 volts and still go short circuit at 230 volts. Heat damaged insulation can resist 12 volts but not 230 volts.
Signs inform. they do NOT prevent.
Some years ago a colleague and I came close to serious micro-wave burns when a ship's captain ignored signs and turned the RADAR from standby to run. We had removed the waveguide ( the pipe that takes the microwave energy up to aerial ) to acess the internals to test and measure the scan drives and the magnatron was pointing straight at us.
His "excuse" was that the maker's label said " Put on standby for 5 minutes before running" which contradicted our safety sign of "Leave on Standy DO NOT RUN"
http://www.moeller.net/en/company/profile/history/history02.jsp
Simple - TLC don't know what they're talking about!
Thanks- that seems clear enough! However, if you ask Mr Google about this, you'll find that TLC appear to be far from alone!
Kind Regards, John
I suspect that Eaton Corporation, who own Moeller, are better informed than TLC or many of Mr Google's friends!
Obviously. I was merely making the point that TLC are not the only ones who think that they are selling Klockner-Moeller products. It does seem a bit odd - one would expect that those who create entries in catalogues and on websites would 'blindly' work from current product descriptions, and that many of them would have been in nappies 13 years ago, and hence unlikely to remember the former name
Kind Regards, John
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