not withstanding some contracts/sites demand we use 110v equipment and ban 240v, therefore we cant choose but where we have the choice what is the opinion on what is safer 240v with RCD plug or 110v transformer and lead
240v110
- Thread starter kirkgas
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B
breezer
110
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Do you really want to trust your life to an electromechanical device that has been known to "stick", and that will deliver a high shock voltage (at best around 100 volts, at worst near Uo) in the event of a fault?
How about using an inherently safe system for which, as far as I am aware, there are no reported deaths or injuries directly involving electric shock (there may have been falls from height). Even if an RLVS fails to open the circuit due to a fault - it will not produce a lethal shock voltage in dry conditions, and it provides a substantial degree of protection in wet conditions. The touch voltage is always < 40 volts and typically less than 30 volts.
It also provides some back up to the basic protection (insulation). Direct contact with a line conductor and earth would only deliver 55 volts (63.5 three phase).
You choose
.
How about using an inherently safe system for which, as far as I am aware, there are no reported deaths or injuries directly involving electric shock (there may have been falls from height). Even if an RLVS fails to open the circuit due to a fault - it will not produce a lethal shock voltage in dry conditions, and it provides a substantial degree of protection in wet conditions. The touch voltage is always < 40 volts and typically less than 30 volts.
It also provides some back up to the basic protection (insulation). Direct contact with a line conductor and earth would only deliver 55 volts (63.5 three phase).
You choose
.From memory haven't 240 v tools been banned for industrial use for a long time.
Remember upsetting a guy from Self Changing Gears (do they still exist?) when he turned up to do a job on a gear box and asked where he could plug in his big 240v drill . . . . . All the factory had was 415V 3Ph (for welders) and compressed air. Borrowed him an air drill only to find the morse taper on his drill bit parallel so it fitted his chuck! Safety officer told me 240v was not permitted.
Remember upsetting a guy from Self Changing Gears (do they still exist?) when he turned up to do a job on a gear box and asked where he could plug in his big 240v drill . . . . . All the factory had was 415V 3Ph (for welders) and compressed air. Borrowed him an air drill only to find the morse taper on his drill bit parallel so it fitted his chuck! Safety officer told me 240v was not permitted.
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Could be wrong but I always thought that the preference for 110V equipment wasn't anything to do with the peak voltage. More to do with the need to use an isolating transformer to step the voltage down. No one uses autotransformers on site right?
If the UK was 110V as standard I could see a good safety case for using 240V equipment on site just because it would require a transformer.
I wonder what the practice is in the USA for site tools.
If the UK was 110V as standard I could see a good safety case for using 240V equipment on site just because it would require a transformer.
I wonder what the practice is in the USA for site tools.
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There are many problems in using a split phase supply main being fuses don't blow in pairs and it is a complex question which includes fire risk.
Sorry I was going to say more but I had visitor. In my younger days I connected a farm house to a generator and did not check the earthing which it turned out was centre tapped which resulted in no fuses or MCB’s being fitted to one leg. Fortunately it was corrected before any damage happened.
This is the method used in the USA where the Westinghouse system is used they have a split phase supply. One feeds upstairs, one feeds downstairs and both feed cooker so cooker is still 220 volt. But it was only last year that the last of the old DC supplies in major cities were replaced. They had been retained as lifts etc were DC it seems.
The USA has loads of different ways to deliver power including delta three phase with “Hot Wire” so to compare with USA is not really a good idea.
Other countries like Algeria have used three phase 110 volt and getting equipment to run on 190 volt (Voltage between phases) is hard and we ended up with auto transformers to step up the voltage to 220 for the air conditioners.
If you look at films made in USA you will see they have loads of small transformers on poles as the volt drop problems prevent them using the larger transformers like we use so they have far more high voltage (over 1000v AC) in the street so motor accidents involving high voltage is far more likely (At least it is on films with sparks flying everywhere) than with our transformers housed in little brick built building.
As with all systems they must be looked at as a whole system and not just a single socket and with lower voltages the cable sizes increase and so also does the fire risk. If we look at the 12 volt DC system used in cars we see many fires caused by the electrics and cable sizes to the starter motor are far thicker than those used to feed an electric drill of same power.
In my option we have the balance right between the lower the voltage the bigger fire risk and higher the voltage the bigger the shock risk.
There are some areas where maybe we have got it wrong. Since with a shaver socket we need an isolation transformer and most shavers will work on both 110v and 240v systems we may as well use 110 volt for all shaver outlets?
Sorry going out but sure you can see the problems
Sorry I was going to say more but I had visitor. In my younger days I connected a farm house to a generator and did not check the earthing which it turned out was centre tapped which resulted in no fuses or MCB’s being fitted to one leg. Fortunately it was corrected before any damage happened.
This is the method used in the USA where the Westinghouse system is used they have a split phase supply. One feeds upstairs, one feeds downstairs and both feed cooker so cooker is still 220 volt. But it was only last year that the last of the old DC supplies in major cities were replaced. They had been retained as lifts etc were DC it seems.
The USA has loads of different ways to deliver power including delta three phase with “Hot Wire” so to compare with USA is not really a good idea.
Other countries like Algeria have used three phase 110 volt and getting equipment to run on 190 volt (Voltage between phases) is hard and we ended up with auto transformers to step up the voltage to 220 for the air conditioners.
If you look at films made in USA you will see they have loads of small transformers on poles as the volt drop problems prevent them using the larger transformers like we use so they have far more high voltage (over 1000v AC) in the street so motor accidents involving high voltage is far more likely (At least it is on films with sparks flying everywhere) than with our transformers housed in little brick built building.
As with all systems they must be looked at as a whole system and not just a single socket and with lower voltages the cable sizes increase and so also does the fire risk. If we look at the 12 volt DC system used in cars we see many fires caused by the electrics and cable sizes to the starter motor are far thicker than those used to feed an electric drill of same power.
In my option we have the balance right between the lower the voltage the bigger fire risk and higher the voltage the bigger the shock risk.
There are some areas where maybe we have got it wrong. Since with a shaver socket we need an isolation transformer and most shavers will work on both 110v and 240v systems we may as well use 110 volt for all shaver outlets?
Sorry going out but sure you can see the problems
B
breezer
Not quite right, it is still used in one place in America...........................
(wait for it)
.
Surely you have heard of "Washington DC"
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