50Hz Voltage Question

under8ed

Senior Member
Why must a switch be double pole to begin with? Breaking only one leg turns the appliance off.
However, without the polarized plug, you would have only a 50/50 chance of disconnecting the power from internal components, even though it would be off. What about changing a light bulb with the outer socket energized?
 

mbrooke

Senior Member
Would you really want to break the neutral only?
Ideally you would only break the hot, but in a none polarized outlet you have no control.


But from a safety standpoint, if the appliance has a protective earth or double insulation, what difference would it make?
 

mbrooke

Senior Member
However, without the polarized plug, you would have only a 50/50 chance of disconnecting the power from internal components, even though it would be off. What about changing a light bulb with the outer socket energized?

My understanding is that euro sockets have protected shells, but I do agree with you on that example. But in other applications like a Coffee maker or hair dryer, what difference would it make?
 

AdrianWint

Senior Member
Would you really want to break the neutral only?
Whilst I agree with this from an isolation standpoint, I was very surprised to find recently that (from a standards viewpoint) there is no requirement for a functional switch inside an appliance to break only the live (hot) conductor or to be double pole! Breaking the neutral for functional switching is acceptable.

Now the Engineer in me isn't very happy with that, but thems the rules (at least here in UK/Europe)
 

iwire

Moderator
Staff member
I want to say the brits got two things right: 230 volts and rings. I could wire an entire first floor with one 32 amp circuit feeding washer, dryer, SABC, kitchen, living room ect, ect while still being to code. IMO the most elegant resi practice ever devised.

Typical UK homes only have a few circuits:

1. 32 amp first floor ring

2. 32 amp second floor ring

3. 10amp lighting radial

4. 40 amp cooker

5. 20amp Immersion heater

I thought I had read they were doing away with ring circuits.
 

AdrianWint

Senior Member
I thought I had read they were doing away with ring circuits.
Nope. Amendment No. 3 to the 17th edition of the wiring regulations has just been published (Jan 2015) and the ring final circuit is alive & well.

There is some discussion going on as to whether radials may be more appropriate in some higher consumption areas (kitchen, laundry room etc) but the use of a ring final for the general purpose socket outlets in the more general areas is still the 'norm'.

This discussion relates to the fact that a ring final has a rating of 32A @ 230V ie. just over 7kW. Our washers/dryers tend to have a rating of around 3kW (ie. 13A @ 230V ... the maximum rating of our socket outlets), so connecting a washer & dryer onto a ring final circuit uses a considerable percentage of that circuits capacity for long periods of time..... The question that is being asked "is it appropriate to use these high power devices on a ring circuit or is a radial (home run) more suitable"
 

AdrianWint

Senior Member
I want to say the brits got two things right: 230 volts and rings. I could wire an entire first floor with one 32 amp circuit feeding washer, dryer, SABC, kitchen, living room ect, ect while still being to code. IMO the most elegant resi practice ever devised.

Typical UK homes only have a few circuits:

1. 32 amp first floor ring

2. 32 amp second floor ring

3. 10amp lighting radial

4. 40 amp cooker

5. 20amp Immersion heater

Agreed, but with a slight correction: Domestic lighting circuits are almost always 6A, commercial are frequently 10A. There are often two lighting circuits: one for upstairs & one for downstairs.

It is common to have two or more ring final circuits (which supply socket outlets), however they don't have to be up/down. Common arrangements are: kitchen/every-where-else or left-side-of-house/right-side-of-house or any other split that the installer sees as suitable.
 

Besoeker

Senior Member
Whilst I agree with this from an isolation standpoint, I was very surprised to find recently that (from a standards viewpoint) there is no requirement for a functional switch inside an appliance to break only the live (hot) conductor or to be double pole! Breaking the neutral for functional switching is acceptable.

Now the Engineer in me isn't very happy with that, but thems the rules (at least here in UK/Europe)
That I didn't know.
 

PetrosA

Senior Member
I'm sure the outlawing of plastic consumer units in the near future will be a fun change as well ;)
 

mbrooke

Senior Member
Nope. Amendment No. 3 to the 17th edition of the wiring regulations has just been published (Jan 2015) and the ring final circuit is alive & well.

There is some discussion going on as to whether radials may be more appropriate in some higher consumption areas (kitchen, laundry room etc) but the use of a ring final for the general purpose socket outlets in the more general areas is still the 'norm'.

This discussion relates to the fact that a ring final has a rating of 32A @ 230V ie. just over 7kW. Our washers/dryers tend to have a rating of around 3kW (ie. 13A @ 230V ... the maximum rating of our socket outlets), so connecting a washer & dryer onto a ring final circuit uses a considerable percentage of that circuits capacity for long periods of time..... The question that is being asked "is it appropriate to use these high power devices on a ring circuit or is a radial (home run) more suitable"


In a smaller home I see no problem. The ring (or 32 amp radial) takes advantage of load diversity, so a dedicated 16 or 20amp radial might end up being more cost with little gain.

However, one a side note a 32 amp radial is less subject to DIY abuse than a ring.









Agreed, but with a slight correction: Domestic lighting circuits are almost always 6A, commercial are frequently 10A. There are often two lighting circuits: one for upstairs & one for downstairs.

It is common to have two or more ring final circuits (which supply socket outlets), however they don't have to be up/down. Common arrangements are: kitchen/every-where-else or left-side-of-house/right-side-of-house or any other split that the installer sees as suitable.
Why is the lighting circuit divided up? Just wondering. But my mistake, most consumer units Ive seen on the internet have two or more lighting cirucits at 6 amps, but perosnally if code allows I would do a 10 or 16 amp... of course that would mean larger wire... and I might being missing box fill or switch ratings... and I am sure theres a good reason for 6 amp circuits.



I'm sure the outlawing of plastic consumer units in the near future will be a fun change as well ;)

Your kidding, right? :eek:
 

PetrosA

Senior Member
Your kidding, right? :eek:
Nope. From what I understand there's still some confusion (it takes full effect in Jan. 2016 but metal may already be installed) about whether or not any materials other than steel will be acceptable. There are plastics used in some enclosures that pass a glowing wire test at about 960 Celsius that were originally thought would be accepted, but later clarifications indicate that's not the case.

The only reason this info even stuck in my brain at all (I mean, what US electrician needs to know this?!?) is my interest in AFCI "technology" and how EU countries are reacting to our total immersion in them. When I lived in Poland, I set up a sub panel in my first cafe using a steel enclosure which was later pointed out to me as being "illegal." Only plastic was acceptable and the argument was that there was no way for it to become energized accidentally. Now I see a trend in the opposite direction and the arguments are mostly concerned with glowing arc safety. If, miraculously, we get some reason in our brains here and realize that AFCI technology isn't as great as it was touted to be, I wouldn't be surprised if the powers-that-be start to go after PVC boxes considering how flammable our construction techniques are. I wouldn't have anything against that per se, but I would definitely want to see a new generation of metal device boxes designed.
 

mbrooke

Senior Member
Nope. From what I understand there's still some confusion (it takes full effect in Jan. 2016 but metal may already be installed) about whether or not any materials other than steel will be acceptable. There are plastics used in some enclosures that pass a glowing wire test at about 960 Celsius that were originally thought would be accepted, but later clarifications indicate that's not the case.

So it boils down to glowing connections?



The only reason this info even stuck in my brain at all (I mean, what US electrician needs to know this?!?) is my interest in AFCI "technology" and how EU countries are reacting to our total immersion in them. When I lived in Poland, I set up a sub panel in my first cafe using a steel enclosure which was later pointed out to me as being "illegal." Only plastic was acceptable and the argument was that there was no way for it to become energized accidentally. Now I see a trend in the opposite direction and the arguments are mostly concerned with glowing arc safety. If, miraculously, we get some reason in our brains here and realize that AFCI technology isn't as great as it was touted to be, I wouldn't be surprised if the powers-that-be start to go after PVC boxes considering how flammable our construction techniques are. I wouldn't have anything against that per se, but I would definitely want to see a new generation of metal device boxes designed.

AFCI technology is the biggest fraud on the planet. Europe already has AFCI technology in the forum of RCD. A glowing connection will not be stopped even with an RCD or AFCI.

There are several epic AFCI threads on ET I can link you to, basically everything you wanted to know about them.
 
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