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Hi,
I have a major problem with a ground loop between my home theater PC and my HIFI.
Bazarly enough it is only if i connect up the un-grounded preamp as an intermediary, if i wire straight to the powers the buzz aint there.
anyway back to my question.
I have used every loop blocker i can afford, they help the problem but the buzz is still there.
The only solution I have is to place them on another mains ring. Unfortunatly i have only 1 socket mains ring in my flat and i could not afford another to be fitted.
Yesterday I got a (hopefully) splendid idea. My heating is electrical. I removed one of my storage heaters and am about to manually wire into that ring. It is a special heating only circuit in my flats. This means that nothing but heaters are connected to it...in theory really clean electricity (and heating electricity is cheaper in my flats which is why it is a heater only ring).
Compared to the drain of a 3kw heater the hifi will drain pittance.
Have i discovered a fantastic thing or am i overlooking something?
pros
1) Seperate ringmain to all the other inteferance causing electrical appliances in the building!
2) Cheaper electricity
3) that line is designed to have a huge drain on it so will be wired with better materials
cons
1) probably in breach of my electricity contract.
Hi,
I have a major problem with a ground loop between my home theater PC and my HIFI.
Bazarly enough it is only if i connect up the un-grounded preamp as an intermediary, if i wire straight to the powers the buzz aint there.
anyway back to my question.
I have used every loop blocker i can afford, they help the problem but the buzz is still there.
The only solution I have is to place them on another mains ring. Unfortunatly i have only 1 socket mains ring in my flat and i could not afford another to be fitted.
Yesterday I got a (hopefully) splendid idea. My heating is electrical. I removed one of my storage heaters and am about to manually wire into that ring. It is a special heating only circuit in my flats. This means that nothing but heaters are connected to it...in theory really clean electricity (and heating electricity is cheaper in my flats which is why it is a heater only ring).
Compared to the drain of a 3kw heater the hifi will drain pittance.
Have i discovered a fantastic thing or am i overlooking something?
pros
1) Seperate ringmain to all the other inteferance causing electrical appliances in the building!
2) Cheaper electricity
3) that line is designed to have a huge drain on it so will be wired with better materials
cons
1) probably in breach of my electricity contract.
Peter Scowcroft said:
Well obviously I know SFA about the UK electrical code, but the above statement goes against what the codes here are. Because heating is a single-service, the electrical code allows a smaller conductor to be used. In short, over here, the conductors in a dedicated electrical heating circuit are SMALLER than if the circuit were multi-service and of the same amperage. And of course if you tap into this heater circuit with a plug, you have now made it multi-service and are non-conforming.
Hi,
thanks for answering.
In answer to the first point. It is multipoint access, there are 5 heaters arround my house on the same ring. they are all radio activated and trigger at the same time drawing about 4kw each.
Is that similar to the situation you described as I am unsure.
In relation to the surge values you might have a good point there.
What makes you believe the surge would be any different than the normal supply.
I use a rotel RB-991 amp its built like a steel coated brick, I used to use it near skipton and lightning strikes meant i had to replace the internal fuses every few months but apart from that it was ok. I will fit a surge protector for the first few weeks to be safe.
Any other ideas?
thanks for answering.
In answer to the first point. It is multipoint access, there are 5 heaters arround my house on the same ring. they are all radio activated and trigger at the same time drawing about 4kw each.
Is that similar to the situation you described as I am unsure.
In relation to the surge values you might have a good point there.
What makes you believe the surge would be any different than the normal supply.
I use a rotel RB-991 amp its built like a steel coated brick, I used to use it near skipton and lightning strikes meant i had to replace the internal fuses every few months but apart from that it was ok. I will fit a surge protector for the first few weeks to be safe.
Any other ideas?
When do you listen to your music?
Storage heater circuits are usually on a timeswitch arranged to be on for a few hours during the night, when the heaters are 'charged' - that's why the juice is cheaper.
There's nothing to stop you overriding the switch, but you will then have to switch your heaters manually.
There's also the question of fusing - 13A socket radial circuits must be fused at 15A, and your heater cct may well have higher rating fuses (or MCBs).
If you want to take this route, you would have to tap off the supply prior to the timeswitch and fit a consumer unit to feed the sockets, in which case you'd be in exactly the same position as running another ring!
Storage heater circuits are usually on a timeswitch arranged to be on for a few hours during the night, when the heaters are 'charged' - that's why the juice is cheaper.
There's nothing to stop you overriding the switch, but you will then have to switch your heaters manually.
There's also the question of fusing - 13A socket radial circuits must be fused at 15A, and your heater cct may well have higher rating fuses (or MCBs).
If you want to take this route, you would have to tap off the supply prior to the timeswitch and fit a consumer unit to feed the sockets, in which case you'd be in exactly the same position as running another ring!
There are two heater circuits in my house, one is on a timer one is 24hr, I still get the cheap juice (though not as) on the 24hr.
I have removed one of the storage heaters so all i need to do is attach a plug to the wires I left out.
So i think i am getting a seperate ringmain with cleaner electricity for the price or wiring a new plug!
I have never been one to care about fuses much anyway, I have also been repeatably electrocuted, but that is completely unrelated
I have removed one of the storage heaters so all i need to do is attach a plug to the wires I left out.
So i think i am getting a seperate ringmain with cleaner electricity for the price or wiring a new plug!
I have never been one to care about fuses much anyway, I have also been repeatably electrocuted, but that is completely unrelated
I did submit a reply pointing out the potential danger of taking supplies from different phases, the requirement to have the modifications inspected (at considerable expense), and the likelihood that the result would be no 'cleaner' than the present supply, but it seems to have been lost in the aether!
Hi,
sorry for no update, i forgot quite how many websites i posted this question on.
I set it up, not even a little problem!
The buzz is gone, the sound is slightly cleaner, the juice is cheaper, and I can turn my hifi of from the wall(the old plug was to concealed!)
all in all a total sucess.
I just have to remember to rip it all out before i sell the house.
Thanks for the advice and concern.
sorry for no update, i forgot quite how many websites i posted this question on.
I set it up, not even a little problem!
The buzz is gone, the sound is slightly cleaner, the juice is cheaper, and I can turn my hifi of from the wall(the old plug was to concealed!)
all in all a total sucess.
I just have to remember to rip it all out before i sell the house.
Thanks for the advice and concern.
Now I am scared!
Did you check that the 'new' supply was on the same phase as the old one - if not, you could have 440V appearing across your gear. Is it correctly fused? Has it been inspected and 'signed off' by a registered electrician (required by regulations now). Remember that if anyone is elecrocuted, or there's a fire, then you will be responsible, and will not be insured!
If the buzz has now gone, I'd be 90% sure that there's a fault on your old supply (or something connected to it), which should be investigated and corrected.
Please think about this carefully
Cheers,
Dave.
Did you check that the 'new' supply was on the same phase as the old one - if not, you could have 440V appearing across your gear. Is it correctly fused? Has it been inspected and 'signed off' by a registered electrician (required by regulations now). Remember that if anyone is elecrocuted, or there's a fire, then you will be responsible, and will not be insured!
If the buzz has now gone, I'd be 90% sure that there's a fault on your old supply (or something connected to it), which should be investigated and corrected.
Please think about this carefully
Cheers,
Dave.
Thanks for the concern Dave,
If i could afford to have it done properly I would have had it done.
I'm skint which is why I am posting here.
I decided to rely on my luck, I guessed. not the most mature of approaches I know. I assumed that if crossing grounds in alternate phase supplies was so dangerous they would not make it so easy to do. If my radiators were using a different phase and I place a metal Item on it wired to the main supply that would cross phase the grounds.
No builder would allow something that dangerous to happen so easily.
I assumed therefore the phases woud be matched, my method may be negotiable but the results are fine.
If there was cross phasing I am sure I would have noticed by now (I am sure my hifi would show some signs of being run at twice the voltage)
I am pretty sure the buzzing was due to a ground loop, the buzz was about 50hz and went when the earths were removed (not a situation I left my hifi in for long an earth has been reconnected.
My hifi is fused properly but grounded through my PC via the interconnect. I have been told that is ok. I am not convinced that if required the interconnect could take the neccersary charge.
I just have to remember if my PC goes bang, not to lick the hifi.
I assure you, I thoink about everything carefully. I just draw different conclusions to most people =-)
If i could afford to have it done properly I would have had it done.
I'm skint which is why I am posting here.
I decided to rely on my luck, I guessed. not the most mature of approaches I know. I assumed that if crossing grounds in alternate phase supplies was so dangerous they would not make it so easy to do. If my radiators were using a different phase and I place a metal Item on it wired to the main supply that would cross phase the grounds.
No builder would allow something that dangerous to happen so easily.
I assumed therefore the phases woud be matched, my method may be negotiable but the results are fine.
If there was cross phasing I am sure I would have noticed by now (I am sure my hifi would show some signs of being run at twice the voltage)
I am pretty sure the buzzing was due to a ground loop, the buzz was about 50hz and went when the earths were removed (not a situation I left my hifi in for long an earth has been reconnected.
My hifi is fused properly but grounded through my PC via the interconnect. I have been told that is ok. I am not convinced that if required the interconnect could take the neccersary charge.
I just have to remember if my PC goes bang, not to lick the hifi.
I assure you, I thoink about everything carefully. I just draw different conclusions to most people =-)
With respect, I don't think you've grasped the situation at all.
Storage heaters with boost fans (which you seem to have) are run from two seperate supplies, which could be on different mains phases. The design of the heater and the installation ensure that there's adequate insulation to cope with the potential 440V PD. This has nothing to do with earthing!
If the supplies are on different phases, the phase ('live') connection to your amp may be at 440V with respect to that of another appliance. The insulation of normal domestic equipment is only designed for 240V, so cannot be considered adequate for this condition.
I'm not sure what you mean by 'cross-phasing' earth connections - the earths of both supplies should be solidly connected to the same point where the supply enters the building - if there is a significant difference between them, you have a serious fault, and should not use either supply until the installation has been inspected. That's one reason for my suggesting that there may indeed be a fault - you are in theory using the same earth, so any problem with one supply should still occur with the other.
Now considering that you may have an installation fault, and that your amp is earthed 'through' your computer, what happens if a fault leaves 440V on the metalwork of your computer? Will the connection stand the current before your (overrated) fuses blow?
I could add a lot more, but will just repeat that you could be liable to prosecution if your work injured or killed anyone, especially as it hasn't been inspected.
Familiarise yourself with the IEE regs (and their reasonoing) before you decide that your work is safe.
It's your funeral! (Hopefully not
)
Storage heaters with boost fans (which you seem to have) are run from two seperate supplies, which could be on different mains phases. The design of the heater and the installation ensure that there's adequate insulation to cope with the potential 440V PD. This has nothing to do with earthing!
If the supplies are on different phases, the phase ('live') connection to your amp may be at 440V with respect to that of another appliance. The insulation of normal domestic equipment is only designed for 240V, so cannot be considered adequate for this condition.
I'm not sure what you mean by 'cross-phasing' earth connections - the earths of both supplies should be solidly connected to the same point where the supply enters the building - if there is a significant difference between them, you have a serious fault, and should not use either supply until the installation has been inspected. That's one reason for my suggesting that there may indeed be a fault - you are in theory using the same earth, so any problem with one supply should still occur with the other.
Now considering that you may have an installation fault, and that your amp is earthed 'through' your computer, what happens if a fault leaves 440V on the metalwork of your computer? Will the connection stand the current before your (overrated) fuses blow?
I could add a lot more, but will just repeat that you could be liable to prosecution if your work injured or killed anyone, especially as it hasn't been inspected.
Familiarise yourself with the IEE regs (and their reasonoing) before you decide that your work is safe.
It's your funeral! (Hopefully not
)Me again!
If you can assure us that you have done the following tests (which are required under part P of the Building Regulations), I shall stop pestering you! Note the requrements of part b, especially separation of circuits, earhing and bonding arrangements and earth loop impedence.
a. Inspected ... to
verify that the components are:
i) made in compliance with
appropriate British Standards or
harmonised European Standards;
ii) selected and installed in
accordance with BS 7671
(including consideration of
external influences such as the
presence of moisture);
iii) not visibly damaged or defective
so as to be unsafe.
b. Tested to check satisfactory
performance in relation to continuity
of conductors, insulation resistance,
separation of circuits, polarity,
earthing and bonding arrangements,
earth fault loop impedance and
functionality of all protective devices
including residual current devices.
If you can assure us that you have done the following tests (which are required under part P of the Building Regulations), I shall stop pestering you! Note the requrements of part b, especially separation of circuits, earhing and bonding arrangements and earth loop impedence.
a. Inspected ... to
verify that the components are:
i) made in compliance with
appropriate British Standards or
harmonised European Standards;
ii) selected and installed in
accordance with BS 7671
(including consideration of
external influences such as the
presence of moisture);
iii) not visibly damaged or defective
so as to be unsafe.
b. Tested to check satisfactory
performance in relation to continuity
of conductors, insulation resistance,
separation of circuits, polarity,
earthing and bonding arrangements,
earth fault loop impedance and
functionality of all protective devices
including residual current devices.
I am getting a lot of different info from different places.
I got informed by the zerogain lot that the problem with my setup is that I am sharing an earth with a supply that may be phased differently.
My entire hifi is on the heater supply so there would be no cross phasing (I assume). The only connection between the two supplies is a shared earth through the interconnect.
If you are saying there is no problem with sharing an earth then I am getting confused what the prob is?
Why is this setup dangerous?
If you can convince me I am doing something bad then I will get this checked, you may even save my life!
As it is alot of electritians seem to take a lot less care than me. The heater I had removed one of the main heating elements was selotaped in place. When I removed the cover the heating element fell out and one of the connections came off. When trained proffesionals can do things like that I do not see problems with what i do.
I would appreciate it if you would explain why what I have done can be considered dangerous.
If I am doing something wrong I would really like to know, but unless I know why I am
I got informed by the zerogain lot that the problem with my setup is that I am sharing an earth with a supply that may be phased differently.
My entire hifi is on the heater supply so there would be no cross phasing (I assume). The only connection between the two supplies is a shared earth through the interconnect.
If you are saying there is no problem with sharing an earth then I am getting confused what the prob is?
Why is this setup dangerous?
If you can convince me I am doing something bad then I will get this checked, you may even save my life!
As it is alot of electritians seem to take a lot less care than me. The heater I had removed one of the main heating elements was selotaped in place. When I removed the cover the heating element fell out and one of the connections came off. When trained proffesionals can do things like that I do not see problems with what i do.
I would appreciate it if you would explain why what I have done can be considered dangerous.
If I am doing something wrong I would really like to know, but unless I know why I am
OK
As I mentioned, there should be no difference between the earths - as there is (your buzz has gone), there's a problem somewhere with your installation. In theory, you are more likely to have an earth loop now, as you are supposedly using two earth returns. I suspect that your original supply isn't correctly earthed - I may be wrong, but it needs checking out. The whole premises forms a Faraday cage which should be equipotentially bonded to protect anyone in it.
The 'phase' danger is that your hi-fi is on one phase and other gear (your computer, or perhaps lamps, etc.) on another. That can lead to high voltages between the two lots of appliances, which are not sufficiently protected in case of faults. Suppose you are leaning on your amp whilst switching a lamp on, and there's a fault - the 440V ends up passing through you. The principle is that you shouldn't be able to touch gear running on both phases at once, unless it's designed to allow for this.
Fusing is there to protect the installation from fire. Your 'new' cct must be correctly fused as a radial 13A supply (which it now is), taking into account the cable used and the corresponding voltage drop.
The earth loop impedence must be low enough to blow the fuse and / or throw the RCD in case of a phase to earth fault. This can only be checked with the proper equipment.
The fact that professionals do sloppy and dangerous work sometimes doesn't excuse you from working safely. In any case, how do you know that the sellotape repair was carried out by a professional?
I could go into some depth as to why what you are doing is potentially dangerous, but the principles require understanding of some theory which you don't seem to have grasped. It is for exactly this reason that significant alterations must now be inspected by personnel who have demonstrated that they do know what they are doing!
It's possible that your idea could be carried out safely, but from your description I'm far from convinced that that's so at present.
BTW, what has convinced you that fuses are not very important? I'm all in favour of independent thinking, but when one reaches conclusions which are diametrically at odds with those of experts, it's time to check that one's first principles are correct.
Your hum can be cured safely without resorting to potentially lethal 'solutions'.
As I mentioned, there should be no difference between the earths - as there is (your buzz has gone), there's a problem somewhere with your installation. In theory, you are more likely to have an earth loop now, as you are supposedly using two earth returns. I suspect that your original supply isn't correctly earthed - I may be wrong, but it needs checking out. The whole premises forms a Faraday cage which should be equipotentially bonded to protect anyone in it.
The 'phase' danger is that your hi-fi is on one phase and other gear (your computer, or perhaps lamps, etc.) on another. That can lead to high voltages between the two lots of appliances, which are not sufficiently protected in case of faults. Suppose you are leaning on your amp whilst switching a lamp on, and there's a fault - the 440V ends up passing through you. The principle is that you shouldn't be able to touch gear running on both phases at once, unless it's designed to allow for this.
Fusing is there to protect the installation from fire. Your 'new' cct must be correctly fused as a radial 13A supply (which it now is), taking into account the cable used and the corresponding voltage drop.
The earth loop impedence must be low enough to blow the fuse and / or throw the RCD in case of a phase to earth fault. This can only be checked with the proper equipment.
The fact that professionals do sloppy and dangerous work sometimes doesn't excuse you from working safely. In any case, how do you know that the sellotape repair was carried out by a professional?
I could go into some depth as to why what you are doing is potentially dangerous, but the principles require understanding of some theory which you don't seem to have grasped. It is for exactly this reason that significant alterations must now be inspected by personnel who have demonstrated that they do know what they are doing!
It's possible that your idea could be carried out safely, but from your description I'm far from convinced that that's so at present.
BTW, what has convinced you that fuses are not very important? I'm all in favour of independent thinking, but when one reaches conclusions which are diametrically at odds with those of experts, it's time to check that one's first principles are correct.
Your hum can be cured safely without resorting to potentially lethal 'solutions'.
Please understand that electricity is dangerous. It kills by electrocution and it kills by fire. That is why there are carefully thought out regulations.
Whether, or not, what you have done is dangerous (and it certainly looks as though it is), you can forget any ideas you had about your dwelling being insured. Any insurance assessor sifting through the smoke-charred rubble and seeing what you have done will absolve all responsibility, leaving you personally liable for any and all damage (including loss of life). If you live in a block of flats, that could be expensive.
Wouldn't it be easy to check if different phases are in use? Just stick meter probes into different sockets at the same time and see if you can get 440V. Probably need an extension cord. Woud this little test provide answers for the worst danger, the possibility of Peter being a conductor of 440V?
Or is this most foolish idea yet?
Regards
Or is this most foolish idea yet?
Regards
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