Re: LED as power on indicator with AC Mains Supply
Posted: Wed Feb 17, 2010 3:08 pm
OK Guys,
Transformers are yesterdays solution to this specific problem.
AFAIK no power strip manufacturer employs that approach.
Why? Mainly cost, but also bulk, & difficulty in mounting.
Am I pushing things in terms of current demand?
In the judgment of a conservative technician, perhaps.
In my judgement, no.
In the judgement of your average non-tech user, NO.
I'll explain; In my experience it's not unusual to have folk mention that they have certain circuits in their homes, that are prone to overload tripping of the main switchboard circuit breakers (this includes some new homes).
Most often its the laundry where a drier, washing machine & iron might be simultaneously in use. What do they do, just be careful because the trip out is a nuisance.
Similarly I know of folk who have 6-way & 8-way power strips crammed with leads to various appliances who confide that they sometimes trip the protection mcb. They realise they are pushing things & generally just exercise more care because the trip out device takes some time to cool & allow a reset.
That's the real world at least as I see it.
I am sure however this is a long way from the set up in any electrical technicians home!
My mains circuit is 15A rated.
My power strip is 10A rated.
Until this particular power strip suffered a component failure, probably surge related, (remember the mcb did not trip) I had encountered zero problems over a 5 year period. Now that does not sound like a marginal application to me.
Regarding power strip design generally; it looks to me as though some manufacturers have solved the technical problems of indication, surge protection & overload protection quite well. Otherwise I am sure we would all be aware of "power strip issues".
Contributors to this tread have made some great suggestions: splitting into a seperate unit the control unit, indicating power on, off, off with alarm, & "on+on".
If this was a mission critical application I'd be encouraged to follow such lines maybe.
OTOH, if I accept that a small chest freezer is only "sort of" mission critical, then my simplest remedy is to buy a power strip with indication & overload protection only, or better yet overload protection only.
Regarding fire risk, I suspect this is over stated, all the power strips employing an internal circuit board, to offer more sophisticated features, potentially have failure prone components that can short. They appear however not to be considered as fire risks, is this due to the mounting or that fires are in practice very rarely started in this way.
I don't know how many are fused, but since a fuse failure would mean for most folk a replacement unit was required, a conventional fuse does not add much other than an extra component.
How "safe is Mr Al's solution" I recall he specified a fuse but I am unsure what would happen if the fuse was omitted.
Peter O
Transformers are yesterdays solution to this specific problem.
AFAIK no power strip manufacturer employs that approach.
Why? Mainly cost, but also bulk, & difficulty in mounting.
Am I pushing things in terms of current demand?
In the judgment of a conservative technician, perhaps.
In my judgement, no.
In the judgement of your average non-tech user, NO.
I'll explain; In my experience it's not unusual to have folk mention that they have certain circuits in their homes, that are prone to overload tripping of the main switchboard circuit breakers (this includes some new homes).
Most often its the laundry where a drier, washing machine & iron might be simultaneously in use. What do they do, just be careful because the trip out is a nuisance.
Similarly I know of folk who have 6-way & 8-way power strips crammed with leads to various appliances who confide that they sometimes trip the protection mcb. They realise they are pushing things & generally just exercise more care because the trip out device takes some time to cool & allow a reset.
That's the real world at least as I see it.
I am sure however this is a long way from the set up in any electrical technicians home!
My mains circuit is 15A rated.
My power strip is 10A rated.
Until this particular power strip suffered a component failure, probably surge related, (remember the mcb did not trip) I had encountered zero problems over a 5 year period. Now that does not sound like a marginal application to me.
Regarding power strip design generally; it looks to me as though some manufacturers have solved the technical problems of indication, surge protection & overload protection quite well. Otherwise I am sure we would all be aware of "power strip issues".
Contributors to this tread have made some great suggestions: splitting into a seperate unit the control unit, indicating power on, off, off with alarm, & "on+on".
If this was a mission critical application I'd be encouraged to follow such lines maybe.
OTOH, if I accept that a small chest freezer is only "sort of" mission critical, then my simplest remedy is to buy a power strip with indication & overload protection only, or better yet overload protection only.
Regarding fire risk, I suspect this is over stated, all the power strips employing an internal circuit board, to offer more sophisticated features, potentially have failure prone components that can short. They appear however not to be considered as fire risks, is this due to the mounting or that fires are in practice very rarely started in this way.
I don't know how many are fused, but since a fuse failure would mean for most folk a replacement unit was required, a conventional fuse does not add much other than an extra component.
How "safe is Mr Al's solution" I recall he specified a fuse but I am unsure what would happen if the fuse was omitted.
Peter O