Author Topic: Not dying in a house with no ground  (Read 5615 times)

0 Members and 1 Guest are viewing this topic.

Offline JoeO

  • Frequent Contributor
  • **
  • Posts: 527
  • Country: us
  • I admit to being deplorable
Re: Not dying in a house with no ground
« Reply #25 on: February 20, 2018, 04:25:35 pm »
If you have grounding and no GFCI, the current on a fault appliance can happily return at high levels on the earth cabling. Such things can easily generate a fire.
Moreover, if you ground yourself for ESD protection and touch a live wire, it can kill you if there is no GFCI.

Do American's not put fuses into anything?

Every plug is fused in the UK, whether it has an Earth or not.  Further each circuit on the mains is fused at the fuse box.  In addition (some times instead of fuse) there are RCD trips.
No, we don't fuse anything.  It saves on costs.
The day Al Gore was born there were 7,000 polar bears on Earth.
Today, only 26,000 remain.
 

Offline rsjsouza

  • Super Contributor
  • ***
  • Posts: 5980
  • Country: us
  • Eternally curious
    • Vbe - vídeo blog eletrônico
Re: Not dying in a house with no ground
« Reply #26 on: February 20, 2018, 04:40:24 pm »
I am familiar with the NEC (although not a professional in the area) and know that drussell's points are sound. A grandfathered electrical installation does not make you liable if there are no explicit problems with it - something quite unusual to happen, given that 100 year-old houses are almost guaranteed to have had major renovations at a certain point in their lifetime.

Regarding the problem at hand; I have lived most of my life in an apartment building without ground (the feeder was a three-phase 380/220) and the rare occasions I was shocked by an appliance it was entirely its fault (also by my electronic experiences, but that was entirely my fault :) ) - therefore, it is not a "death trap" or anything of the sorts if it is well maintained.

As for grounding your house on the feeder installation: you can't guarantee it won't be disconnected at a sudden if the maintenance crews need to work on it (not to mention it may be illegal, but I don't know the details). Also, as others have mentioned, you are connecting your ground to a system much more exposed to HV faults or electric discharges, which can raise the voltages to dangerous levels. I have seen this happen and obliterate electronic equipments (Audio equipment, TVs, VCRs...) in entire neighbourhoods - usually other appliances (fans, lamps, blenders, etc.) are much more resilient to these.

As for fuses and circuit breakers: they are usually dimensioned to protect the wiring against overheat, not the person or the appliance.

Quote
Every plug is fused in the UK, whether it has an Earth or not.

Yeah, that's because you folks use the strange-to-us method of essentially stiffly connecting the whole house directly to the mains feeders and letting the plugs try to play mediator.  :)

Your system seems insane to us, and our system seems insane to you, but they both work.
I don't quite get that: do you mean that in UK there is no main circuit breaker box?

Vbe - vídeo blog eletrônico http://videos.vbeletronico.com

Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 

Offline Nusa

  • Super Contributor
  • ***
  • Posts: 2416
  • Country: us
Re: Not dying in a house with no ground
« Reply #27 on: February 20, 2018, 04:50:51 pm »
In the US, ungrounded three-prong outlets are NOT legal (other than GFCI installations as mentioned above), although in practice you run across them all the time in older housing. If that's the case you CAN force the issue with your landlord. The most likely end result is they'll revert any 3-prong outlets back to 2-prong outlets rather than rewiring, which satisfies the law but makes it less convenient to use. You don't get what you really want, and a rent increase may be in your future.

As for the power-pole ground, if it's utility owned, don't even think about it. They will not react well when they notice it. Drive your own grounding rod if you go that route.
 

Online helius

  • Super Contributor
  • ***
  • Posts: 3633
  • Country: us
Re: Not dying in a house with no ground
« Reply #28 on: February 20, 2018, 05:16:30 pm »
Older US houses, before the grounded NEMA 5 connectors introduced in the 1960s, it was still typical for the fuse box itself to be grounded to multiple points including the service neutral, the cold water main, and a local grounding rod. At the time, metal armored "BX" electrical cabling was widely used for its safety and strength, which connected the fuse box to outlet enclosures in the walls.
These grounding provisions were used on almost all houses because they were required for reliable phone service—a lightning arrestor in the telco network interface provides a path from the copper loop to local ground. As 3-prong NEMA 5 connectors on appliances became the norm, plug adapters for older NEMA 1 outlets in grounded box enclosures were sold to be able to use them without rewiring the house or the appliance. They are green rubber plugs with a grounding wire attached, which is screwed into the body of the outlet, and thereby grounded to the enclosure.
 

Offline paulca

  • Super Contributor
  • ***
  • Posts: 4003
  • Country: gb
Re: Not dying in a house with no ground
« Reply #29 on: February 22, 2018, 08:16:31 am »
Quote
Every plug is fused in the UK, whether it has an Earth or not.

Yeah, that's because you folks use the strange-to-us method of essentially stiffly connecting the whole house directly to the mains feeders and letting the plugs try to play mediator.  :)

Your system seems insane to us, and our system seems insane to you, but they both work.
I don't quite get that: do you mean that in UK there is no main circuit breaker box?

Yea.  We have lots of fuses.  Plugs have fuses, fixed installation points (washing machines, etc.) have fuses, each mains circuit (downstairs plug ring, upstairs plug ring, downstairs lights, upstairs lights, cooker, shower, etc. etc.) have a individual fuse (and an optional trip), then you have the mains fuse, usually 100A.  If you blow that the electric utility people have to change it and there is usually a fine if you overloaded it.

Yes these protect the wiring not the person (with the exception of the very common and probably mandatory on new installations RCD trip).

Still it's much easier to replace a fuse in a plug than the meter box.  Besides.  A 15A fault current will not blow a 30A plug ring fuse, but it will set fire to the 3A mains lead to the device.

Having individually fused circuits means if you want to work on a downstairs light fitting you can pull the fuse and put it in your pocket while leaving the remainder of the power on.
« Last Edit: February 22, 2018, 08:20:55 am by paulca »
"What could possibly go wrong?"
Current Open Projects:  STM32F411RE+ESP32+TFT for home IoT (NoT) projects.  Child's advent xmas countdown toy.  Digital audio routing board.
 
The following users thanked this post: rsjsouza

Offline Ian.M

  • Super Contributor
  • ***
  • Posts: 12807
Re: Not dying in a house with no ground
« Reply #30 on: February 22, 2018, 08:51:42 am »
The days of distribution panels with plug in fuses (or even plug in breakers) in the UK are mostly long gone.   The formerly common old Wilex panels with either cartridge or rewirable fuses or with retrofitted breakers, a wooden frame and an open back aren't permitted under current  IEE Wiring Regulations (UK equivalent to US NEC) and although some units protected by a 60A utility company fuse may be grandfathered in, any rewiring work is likely to require their replacement.  Newer metal or flame retardant plastic backed Wilex breaker panels are still compliant but IIRC there aren't any pluggable RCBOs for them so RCD protection cant be retrofitted at the panel.

Extreme caution should be used if investigating other brands of old distribution panels with rewirable fuses as some used friable asbestos cloth in the rewirable fuse carrier.  Removal by a specialist Asbestos remediation company followed by compete replacement is probably cheaper than replacing individual fuses with cartridge fuse carriers (if compatible ones are available) and cleaning the Asbestos residue from the existing panel.

The current practice in UK consumer units seems to be DIN rail based breakers +one or more  RCBs  feeding them or individual RCBOs.   There is no way to physically disconnect *and* isolate a circuit without tools, (though you could trip a breaker use an appropriate lockout/tagout device to secure it in the OFF position) and actually pulling a breaker rather than disconnecting its load circuit cabling would leave the tag of the live busbar feeding it exposed.
« Last Edit: February 22, 2018, 08:59:20 am by Ian.M »
 

Offline paulca

  • Super Contributor
  • ***
  • Posts: 4003
  • Country: gb
Re: Not dying in a house with no ground
« Reply #31 on: February 22, 2018, 09:27:07 am »
There is no way to physically disconnect *and* isolate a circuit without tools, (though you could trip a breaker use an appropriate lockout/tagout device to secure it in the OFF position) and actually pulling a breaker rather than disconnecting its load circuit cabling would leave the tag of the live busbar feeding it exposed.

I worked as a sparks mate many, many years ago and this would be quite worrying.  When you enter a new property that has the power on to do some work but there is a fuse pulled, sitting on top of the consumer unit it would be all too tempting to simply plug it back in.  Immediately killing the guy working in the attic.

We were always told in such a situation to walk round the whole house shouting your intent to put the fuse back in.  We were also told when we wanted to pull a fuse to do work to put the fuse in our pocket so it can't be replaced by someone while you are working.

What is stopping someone simply thinking the breaker was left off by the last person and flipping it back on?  Unless there is a key, even a plastic keyed tool that you can take with you.

I suppose an alternative is to put a sticker on the breaker saying "DO NOT ENERGIZE".
"What could possibly go wrong?"
Current Open Projects:  STM32F411RE+ESP32+TFT for home IoT (NoT) projects.  Child's advent xmas countdown toy.  Digital audio routing board.
 

Offline Ian.M

  • Super Contributor
  • ***
  • Posts: 12807
Re: Not dying in a house with no ground
« Reply #32 on: February 22, 2018, 09:54:18 am »
That's why you need the correct lockout/tagout device for the breaker if you are working on the circuit as a  professional.   As an amateur without the manufacturer's lockout/tagout device, or as a professional without the right lockout/tagout device - if you cant secure the consumer unit, you'll have to disconnect its load circuit at the breaker and tape up the wire end(s) so they cant make contact, then replace the consumer unit cover.

A 'DO NOT ENERGISE' sticker without physically disconnecting the circuit is only appropriate if all other people with *ANY* access are qualified and you trust them 100% - 'with your wife and your life' level of trust, and the HSE will throw a fit if anything goes wrong.
 

Offline rsjsouza

  • Super Contributor
  • ***
  • Posts: 5980
  • Country: us
  • Eternally curious
    • Vbe - vídeo blog eletrônico
Re: Not dying in a house with no ground
« Reply #33 on: February 22, 2018, 12:35:45 pm »
Quote
Every plug is fused in the UK, whether it has an Earth or not.

Yeah, that's because you folks use the strange-to-us method of essentially stiffly connecting the whole house directly to the mains feeders and letting the plugs try to play mediator.  :)

Your system seems insane to us, and our system seems insane to you, but they both work.
I don't quite get that: do you mean that in UK there is no main circuit breaker box?

Yea.  We have lots of fuses.  Plugs have fuses, fixed installation points (washing machines, etc.) have fuses, each mains circuit (downstairs plug ring, upstairs plug ring, downstairs lights, upstairs lights, cooker, shower, etc. etc.) have a individual fuse (and an optional trip), then you have the mains fuse, usually 100A.  If you blow that the electric utility people have to change it and there is usually a fine if you overloaded it.

Yes these protect the wiring not the person (with the exception of the very common and probably mandatory on new installations RCD trip).

Still it's much easier to replace a fuse in a plug than the meter box.  Besides.  A 15A fault current will not blow a 30A plug ring fuse, but it will set fire to the 3A mains lead to the device.

Having individually fused circuits means if you want to work on a downstairs light fitting you can pull the fuse and put it in your pocket while leaving the remainder of the power on.
Quite interesting; thanks for the clarification.

About your last point, though: in a light fixture, is the fuse on the fixture or in the wiring that leads to it? If it is in the fixture, how do you replace the fixture itself without disconnecting the whole house?
Vbe - vídeo blog eletrônico http://videos.vbeletronico.com

Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 

Offline paulca

  • Super Contributor
  • ***
  • Posts: 4003
  • Country: gb
Re: Not dying in a house with no ground
« Reply #34 on: February 22, 2018, 12:56:40 pm »
Quote
Every plug is fused in the UK, whether it has an Earth or not.

Yeah, that's because you folks use the strange-to-us method of essentially stiffly connecting the whole house directly to the mains feeders and letting the plugs try to play mediator.  :)

Your system seems insane to us, and our system seems insane to you, but they both work.
I don't quite get that: do you mean that in UK there is no main circuit breaker box?

Yea.  We have lots of fuses.  Plugs have fuses, fixed installation points (washing machines, etc.) have fuses, each mains circuit (downstairs plug ring, upstairs plug ring, downstairs lights, upstairs lights, cooker, shower, etc. etc.) have a individual fuse (and an optional trip), then you have the mains fuse, usually 100A.  If you blow that the electric utility people have to change it and there is usually a fine if you overloaded it.

Yes these protect the wiring not the person (with the exception of the very common and probably mandatory on new installations RCD trip).

Still it's much easier to replace a fuse in a plug than the meter box.  Besides.  A 15A fault current will not blow a 30A plug ring fuse, but it will set fire to the 3A mains lead to the device.

Having individually fused circuits means if you want to work on a downstairs light fitting you can pull the fuse and put it in your pocket while leaving the remainder of the power on.
Quite interesting; thanks for the clarification.

About your last point, though: in a light fixture, is the fuse on the fixture or in the wiring that leads to it? If it is in the fixture, how do you replace the fixture itself without disconnecting the whole house?

In the case of lights the fuse is only in the main fuse box.  Usually a 15A fuse per circuit.  In most normal sized houses there would be "upstairs" and "downstairs" light circuits.  Outdoor lights would usually be separately wired and fused.
"What could possibly go wrong?"
Current Open Projects:  STM32F411RE+ESP32+TFT for home IoT (NoT) projects.  Child's advent xmas countdown toy.  Digital audio routing board.
 
The following users thanked this post: rsjsouza

Offline Ian.M

  • Super Contributor
  • ***
  • Posts: 12807
Re: Not dying in a house with no ground
« Reply #35 on: February 22, 2018, 01:13:01 pm »
UK Lighting circuits are usually *NOT* fused at the light fittings although some multi-bulb decorative fittings may be fused to protect wiring in the fitting of under 1mm2 CSA and/or prevent overload by the substitution of higher wattage bulbs.  They are 5A radial circuits, usually run with 1mm2 flat twin + earth cable, protected by a fuse, breaker or RCBO at the consumer unit.  You'll also see 1.5mm2 cable for long runs.

Higher current lighting circuits are also found in larger dwellings, but they need appropriately rated cables - you cant just pop a 15A breaker in on an old 1mm2 circuit to upgrade it.

In all cases, you'd isolate the circuit as described above.
« Last Edit: February 22, 2018, 01:17:06 pm by Ian.M »
 
The following users thanked this post: rsjsouza

Offline Monkeh

  • Super Contributor
  • ***
  • Posts: 7990
  • Country: gb
Re: Not dying in a house with no ground
« Reply #36 on: February 22, 2018, 01:38:38 pm »
In the case of having ground and no GFCI, a stray 1 amp current on the isolation that goes to ground can generate a fire and not trip any fuse. It all depends on the appliance and the fault mode.

I don't know how it's done in Spain, but we don't use bits of wet string as conductors. A little current passing through the CPC will not cause a bloody fire.
 

Offline paulca

  • Super Contributor
  • ***
  • Posts: 4003
  • Country: gb
Re: Not dying in a house with no ground
« Reply #37 on: February 22, 2018, 03:00:34 pm »
They are 5A radial circuits, usually run with 1mm2 flat twin + earth cable

Opps, yes, 5A, not 15A.

I think sparks call them branch and spur, so the kinds of fan out in a tree with one main line/chain and spurs branching off it.
"What could possibly go wrong?"
Current Open Projects:  STM32F411RE+ESP32+TFT for home IoT (NoT) projects.  Child's advent xmas countdown toy.  Digital audio routing board.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf