Plastic bit on pull cord switches is for insulation/saftey reasons?

[EFLImpudence]

I wonder if its Class I or II - I'm not sure that one could reliably earth (all of) a 'cord' consisting of metal beads presumably strung on something non-conductive. Mind you, are we even certain that they are metal beads (rather than plastic with 'chrome paint')?

I suspect it is all plastic with chrome paint.

Sort of, but all the recent discussion has not been about water causing a problem with the switch but, rather, water potentially turning a pull cord into a conductor (which a metal one already would be).

That's what I meant.

One thing that hasn't been mentioned is that, for very many years, the cords have (presumably) been made of 'man-made-fibres', so any sort of string/cotton/wool/yarn/whatever - so probably far less inclined to get 'soaked in water', even if submerged in the stuff?

You appear to be trying to think of ways the original ridiculous idea can be mitigated.


What happens when an ordinary metal-faced switch fills with water or gets covered in condensation?

 

[JohnW2]

I suspect it is all plastic with chrome paint.

As I implied, I suspect you may be right.

You appear to be trying to think of ways the original ridiculous idea can be mitigated.

Not at all. The ridiculous idea was even more ridiculous when the 'cord couplers' first appeared - since, as has been discussed, they were metal. When they changed to plastic, perhaps some people believed that 'insulation' was one of the purposes - but I was making the point that, even for them the argument has subsequently got far weaker, since for a long time cords have (presumably) been made of a material which probably cannot be 'soaked in water'.

What happens when an ordinary metal-faced switch fills with water or gets covered in condensation?

I'm not quite sure of your point here. If it's a standard (earthed) metal faceplate, then if the switch 'filled with water', the RCD (which should be protecting a bathroom circuit) would presumably trip ... and having exposed earthed metal covered in condensation should not make any difference to anything ... or were you talking/thinking of something else?

Kind Regards, John

 

[EFLImpudence]

I'm not quite sure of your point here. If it's a standard (earthed) metal faceplate, then if the switch 'filled with water', the RCD (which should be protecting a bathroom circuit) would presumably trip ... and having exposed earthed metal covered in condensation should not make any difference to anything ... or were you talking/thinking of something else?

Not really - just giving the 'electric string theorists' something else to worry about.

 

[JohnW2]

Not really - just giving the 'electric string theorists' something else to worry about.

Fair enough - but even they might not be too concerned about exposed earthed metal getting wet.

Kind Regards, John

 

[mattylad]

Perhaps the inside of it is designed with insulated covers etc. to allow the chain to be replaced, rather than the way many string ones are with open switchgear.
Although I have also seen the string ones with a little push toggle type switch in (obviously a pull one instead)

 

[flameport]

An answer might be found in BS 2652 from 1955, if anyone has access to a copy of it.
Was made obsolete decades ago and the number has been reused since, so it's unobtainable in all of the usual places.

Edit - there is one print copy in the world, and it's in New Zealand.

 

[JohnW2]

An answer might be found in BS 2652 from 1955, if anyone has access to a copy of it. Was made obsolete decades ago and the number has been reused since, so it's unobtainable in all of the usual places. Edit - there is one print copy in the world, and it's in New Zealand.

It's a pity that we are not 'back then', since it appears that we could have purchased a copy for 2s 6d (aka 12.5p), including postage...

Cord-Operated Ceiling-Switches (B.S. 2652: 1955). 2s. 6D. Cord-operated ceiling-switches may be of either the surface mounting or semi-recessed type. In Section 1 definitions of the various types of switch are given. Section 2 gives the constructional requirements which apply to all switches for domestic and similar purposes, and also specifies the special requirements for the action and attachment of the operating cord. Section 3 specifies the tests required, including type tests. The electrical tests include current-carrying capacity, endurance, over-voltage and over-current capacity and high-voltage tests.

Kind Regards, John

 

[SUNRAY]

OK - I just sacrificed 20 minutes of my life to finding the answer. It's in BS EN 60669-1:2000+ A2:2008

10.7 Where cord-operated switches are provided with a pull cord, which can be fitted or
replaced by the user, they shall be so designed that it is impossible to touch live parts when
fitting or replacing the pull cord in the normal way.

That's an absolutely brilliant find...

However if that is the reason for fitting the insulator I can think of a glaring error in every single currently available pull switch.

Let me get this straight.
The joint is supposedly there so a user doesn't have to open the switch to replace the string?

So next question: where is a string most likely to break?
I'll offer it's most likely to be due to damage or fraying and the most likely place for a string to fray is where it rubs on something or constantly flexes.
The 2 most likely places for constant flexing and fraying are:
1) the bottom of the string where it enters the pull knob, this is most likely to be repaired by threading the knob back on the string and tying a knot, and
2) at the top where it rubs against the edge of the cover and the only repair is to unscrew the cover and refix or replace the string.

The insulator is irrelevant in both scenarios.

Oh and why would replacement strings come with a joint and a short piece of string if it isn't intended to replace the whole thing?

 

[mattylad]

Your thinking only of the string needing replacement due to breaking.

They have a habit of getting dirty when people with dirty hands coming into the bathroom use them.
So they will be taken off and bleached or replaced for that.

The top bit doesn't get dirty

 

[SUNRAY]

Your thinking only of the string needing replacement due to breaking.

They have a habit of getting dirty when people with dirty hands coming into the bathroom use them.
So they will be taken off and bleached or replaced for that.

The top bit doesn't get dirty

I understand this but how often do people remove and clean the string? I never have but I did once remove the bottom foot or so on one of ours when it got blood on it [and yes it really was a bit too long] equally I've not replaced any strings but have replaced 3 of the 5 switches in the 26 years we've lived here.

 

[mattylad]

Hard question to answer.
Depends how dirty it gets, depending on if the household have dirty hands or not before going, depends if someone in the house is OCD about cleaning or not.
A mucky string can carry loads of germs.

 

[RF Lighting]

Over the years I’ve replaced loads of pull switch strings, especially in rental properties for some reason. I can only think of one where the string has broken inside the switch, and if this is the case, I would just replace the switch rather than try and faf about taking it in bits and springs shooting off all over the place.

Also I’ve had a couple of customers who have changed the string to a different colour just because they like it.

 

[EddieM]

I replaced the lower string with a black one once (so it didn't show the dirt) the upper bit remained white, also the pull was replaced with a pottery lighthouse, which on hindsight is probably incredibly naff. Hey go, no one got hurt.

 

[mattylad]

Personally I dont use the bottom of the string, I pull it from 1/2 way up (oooh errr missus!) so Im not touching a mucky string when leaving the bathroom.

 

[bernardgreen]

How about his and her strings, There are bath rooms with two ( his and her ) wash basins.