Scorched Neutral on shower isolation switch

jodaw

Bruthal wrote: »

If it was touching the steel box if its properly earthed, it should have tripped the RCD when the shower was on, assuming the shower has one in the fuseboard.

Then it looks like it was never properly earthed. Has rcd in distribution. Shower never once tripped it.

No backboxes in house have any sort of grommet

Bruthal

jodaw wrote: »

Then it looks like it was never properly earthed. Has rcd in distribution. Shower never once tripped it.

No backboxes in house have any sort of grommet

Its possible the neutral copper never touched the box or anything earthed.

Bare steel holes with cables through is a real cowboy effort imo. It is not unusual.

jodaw

Bruthal wrote: »

Its possible the neutral copper never touched the box or anything earthed.

Bare steel holes with cables through is a real cowboy effort imo. It is not unusual.

Very cheapo effort in whole house really. Switches and backboxes crooked and any i have seen would have no grommets.

One thing that pisses my off is there were never any circuits ran to hotpress, so an immersion or pumped shower would need a whole new circuit run back to fuseboard

Tuco88

I don't know why fellas don't just put fly leads on all the back boxes/metal clad boxes before installing. Thats what we used to do.

Should the link between the Shower Isolator switch and backbox be the same C.S.A as the line conductor?


Personally I wouldn't really see an issue with 2.5mm^2, as regards on a technically point of view for an Earth fault path should it be the same? Be all is you couldn't possibly get 3 into 1 terminal anyway..

Could he repair the cable insulation with a heavy heat shrink.

Risteard81

Tuco88 wrote: »

Personally I wouldn't really see an issue with 2.5mm^2, as regards on a technically point of view for an Earth fault path should it be the same?

It would only need to be able to sustain the fault current until disconnection occurs (as per the adiabatic equation). So 2.5mm^2 would be absolutely fine for a 6mm^2 cable (or say 4mm^2 for a 10mm^2).


It simply isn't possible to connect 6mm^2 or 10mm^2 conductors to the backbox (without drilling and tapping), and as you point out would never fit in the terminals on the accessories anyway.

Sam Quentin

Can the experts also advise: it's just not good practice turning off shower by main terminal, slamming the shower into a no power lock down instead of turning the shower off with its intended stop button couldn't be good,.am I right!?

Hintel

Sam Quentin wrote: »

Can the experts also advise: it's just not good practice turning off shower by main terminal, slamming the shower into a no power lock down instead of turning the shower off with its intended stop button couldn't be good,.am I right!?

Yes those isolators are best left on all the time anyhow

They're too troublesome when used all the time

2011

I agree with Hintel but, there are plenty of highly qualified and experienced professionals that take an opposing view.

Sleeper12

2011 wrote: »

I agree with Hintel but, there are plenty of highly qualified and experienced professionals that take an opposing view.

I understand your logic behind this but the Fire Officer now recommends the isolation switch be turned off after each shower. His logic is even if isolation switch needs replacing every year or two it's cheaper than repairs after a fire. This isn't a legal requirement. It's a comment he made after an unattended electric shower, turned off, went on fire.

John.G

And yet, while worrying about such trifles, I am quite happy to (legally) shower away merrily in my 14 year old Mira Sport with water spraying everywhere with my nose literally inches away from a 230V cable contained in a "shower proof" plastic box!.

Sleeper12

John.G wrote: »

And yet, while worrying about such trifles, I am quite happy to (legally) shower away merrily in my 14 year old Mira Sport with water spraying everywhere with my nose literally inches away from a 230V cable contained in a "shower proof" plastic box!.

Water resistant rather than waterproof. Hold the full flow of the water over the top of the cover & the RCBO might pop

Bruthal

Sleeper12 wrote: »

I understand your logic behind this but the Fire Officer now recommends the isolation switch be turned off after each shower. His logic is even if isolation switch needs replacing every year or two it's cheaper than repairs after a fire. This isn't a legal requirement. It's a comment he made after an unattended electric shower, turned off, went on fire.

He may as well recommend turning off the DB main switch whenever a house is left unattended too.

John.G

Sleeper12 wrote: »

Water resistant rather than waterproof. Hold the full flow of the water over the top of the cover & the RCBO might pop

My relation's shower would trip the RCBO once or twice a year, I found one of the front cover top securing screws wasn't fitted so I replaced it and the shower hasn't tripped since.

2011

Sleeper12 wrote: »

I understand your logic behind this but the Fire Officer now recommends the isolation switch be turned off after each shower. His logic is even if isolation switch needs replacing every year or two it's cheaper than repairs after a fire. This isn't a legal requirement. It's a comment he made after an unattended electric shower, turned off, went on fire.

The counter argument to what you have stated above is that a fire is far more likely to occur in the first place if the isolator is operated before and after the use of the shower. Although I accept the argument that replacing an isolator every year or two is not that expensive this ignores the fact that the fire that may occur due to the failure of this device is the real cost.

My next point is where does this end? Does the fire officer (or others sharing this view) only insist on this practice for the shower or does it extend to other fixed appliances? If not, why not? Surely only a consistent approach makes sense? In many homes fixed appliances typically include:

• Hob
• Oven
• Boiler
• Intruder alarm
• Immersion
• Zone valves

Also there are many devices that are left plugged in for years in homes up and down the country such as:

• Washing machine
• Tumble dryer
• Dish washer
• Microwave
• TV
• Satellite box

If all of the above are to be unplugged or their isolator switched off it would take at least an hour to leave the house each day:D

As I have already stated, I accept fully that there are differing opinions on this. That is why I made it clear in post #13 that what is stated is just an opinion (by using the words "in my view").

John.G

Does the isolator have to installed in close proximity to the shower or can it be installed at the main board?.

2011

John.G wrote: »

Does the isolator have to installed in close proximity to the shower or can it be installed at the main board?.

It should be local to the appliance it isolates. However there are specific requirements about how and where devices such as this are installed in a bathroom.

Frequently you will see these devices are installed just outside the bathroom.

Bruthal

John.G wrote: »

Does the isolator have to installed in close proximity to the shower or can it be installed at the main board?.

Its function is to isolate the shower to allow safe working on it. Down at DB doesn't do that.

To allow easier wiring of isolator beside showers it was recommended contactors be fitted at the DB and small control wiring up to isolator.

My opinion at the time this is not proper isolation. Very bad actually imo.

I think 10 square with 10 square earth is over the top as well.

John.G

Thanks, would/are you happy to carry out maintenance on a shower with say a pull cord isolator without switching out the RCBO or whatever as a extra precaution even though this wouldn't be considered a isolator as such.

Bruthal

John.G wrote: »

Thanks, would/are you happy to carry out maintenance on a shower with say a pull cord isolator without switching out the RCBO or whatever as a extra precaution even though this wouldn't be considered a isolator as such.

I would anyway. Sometimes the RCBO would be used, for example, changing the isolator.

The way regs are going, they might bring out an isolator for the isolator.


In industrial situations, locks would be used to keep circuits isolated. Domestic it is much easier to keep track of what is happening around the area.

2011

Yes, industrial installations are a very different animal. They require electricians with very different skill sets, which can often require specialist training.

salmocab

2011 wrote: »

Yes, industrial installations are a very different animal. They require electricians with very different skill sets, which can often require specialist training.

I got a call last year from a guy who was turning on power to a shop unit and in the switch room the tag had my number on it from about 3 years beforehand. I had moved company at that stage.

Hintel

Bruthal wrote: »

Its function is to isolate the shower to allow safe working on it. Down at DB doesn't do that.

To allow easier wiring of isolator beside showers it was recommended contactors be fitted at the DB and small control wiring up to isolator.

My opinion at the time this is not proper isolation. Very bad actually imo.

I think 10 square with 10 square earth is over the top as well.

It was ecssa that came up with the idea at the time

I've seen it done recently enough, a bad idea

Crabtree I found to be a good pull cord

Hintel

The 4 types.of.switching

1 Control

2 Isolation

3 Emergency switching

4 Switching off for.mechanical maintenance

In a domestic setting isolation is done locally


In an industrial setting 2 3 and 4 can all be done by a
single local switch I think I'm right in saying

2 and 4 can be done remotely with a lockable device

Sleeper12

The fire officers advice is to turn everything off or unplug it when going to bed. They also advise never using washing machines & dishwashers when in bed or not in the house. This advice you'll ignore if you have a night rate meter.

The advice on turning off the isolation switch for the electric shower if to take into account the idiot factor imo. These are the high IQ people that will tell you "it's been smelling of burning the last few weeks while I shower". Or "I've noticed the burn/scorch mark getting bigger on the shower cover/ pull cord switch for weeks now". The advice is given because some people totally ignore red flag warning signs imo. A shower doesn't usually just spontaneously burst into flames.

Kat1170

Sleeper12 wrote: »

The fire officers advice is to turn everything off or unplug it when going to bed. They also advise never using washing machines & dishwashers when in bed or not in the house. This advice you'll ignore if you have a night rate meter.

The advice on turning off the isolation switch for the electric shower if to take into account the idiot factor imo. These are the high IQ people that will tell you "it's been smelling of burning the last few weeks while I shower". Or "I've noticed the burn/scorch mark getting bigger on the shower cover/ pull cord switch for weeks now". The advice is given because some people totally ignore red flag warning signs imo. A shower doesn't usually just spontaneously burst into flames.

There is often a 'fishy' smell when something electrical is burning. I think the OP even mentioned it.

2011

Sleeper12 wrote: »

The fire officers advice is to turn everything off or unplug it when going to bed.

If by "turn off" you mean using the local isolator and / or unplugging everything I think that we can agree that nobody ever follows this advice.

If you turn off your cooker switch the clock needs to be reset. I don't think that was the manufactures intention, they designed the cooker to be left powered.

What about gas boilers? Do you know anyone that turns them off at the isolator before going to bed?

They also advise never using washing machines & dishwashers when in bed or not in the house. This advice you'll ignore if you have a night rate meter.

I have seen washing machines and other appliances go on fire alright, but never because the isolator was left on when the appliance was not in use.

Sleeper12

Kat1170 wrote: »

There is often a 'fishy' smell when something electrical is burning. I think the OP even mentioned it.

There is, or a rotten egg smell. Point is lots of people continue to use their appliances for weeks despite the warning signs

Bruthal

Hintel wrote: »

It was ecssa that came up with the idea at the time

Yes that`s right I remember now. Very poor method.

10 square is not practical in domestic isolator switches imo though.

If it was 10 square flex, that would help.

Hintel

What would be causing showers to go on fire when not in use

Doesn't seem a likely scenario

meercat

Hintel wrote: »

It was ecssa that came up with the idea at the time

cord

RECI also recommended contactor switching (page6)

https://safeelectric.ie/contractors/wp-content/uploads/sites/2/2018/09/2016dec_news.pdf