Wiring practices

[kwired]

Because the heater should be tested and listed with factory connections and a heat resistent chamber where the switch box might be all DIY installed.

Just what does being installed by a DIY have to do with anything?

I am tired of having to design and install more things every three years around the DIY mistakes (not even mistakes - usually just ignorance) made in the past. We have many stupid rules that are because of people that stuck their noses where they don't belong.

Wall boxes are intended to contain splices and devices - which have a risk of developing heat because of a poor connection. If the risk of developing heat in those situations were not that great we may not even require boxes where junctions happen. If a DIY doesn't install something correctly and burns his house down why should the entire electrical industry have to change their ways to accomodate the DIY that still will not do things right even after the changes?

 

[wtucker]

My wife...and our daughters could very easily have been trapped in a house on fire because that thermostat is located on the same wall as the stairway to the 2nd story.

I hope you've got smoke detectors in the house. Now, get to work on an evacuation plan (maybe get one of those emergency ladders than can be hung on a window sill). Then, practice the plan.

 

[pfalcon]

I have seen more connection failures with the factory heater connections than I have with the field installed connections.

The solution at the switch doesn't become less valued just because there's a worse problem somewhere else.

Just what does being installed by a DIY have to do with anything?

Likelihood of failure; Isolation of liability.

I am tired of having to design and install more things every three years around the DIY mistakes (not even mistakes - usually just ignorance) made in the past. We have many stupid rules that are because of people that stuck their noses where they don't belong.

I agree. But as we always talk about in the heirarchy of safety design - quit trying to make a safer widget when you can remove the widget entirely. As an industry we should stop trying to make 120V switches and outlets safer. Instead we should be questioning why we have one at all.

Wall boxes are intended to contain splices and devices - which have a risk of developing heat because of a poor connection. If the risk of developing heat in those situations were not that great we may not even require boxes where junctions happen.

And a 24V switch doesn't require much more than a plate. Look at your phone and cable service.

If a DIY doesn't install something correctly and burns his house down why should the entire electrical industry have to change their ways to accomodate the DIY that still will not do things right even after the changes?

Honestly, because electrical engineers are part of the electrical industry. And because a core part of being an electrical engineer is to design for safety. Houses are burned down because of faulty wiring and it doesn't matter who's to blame. The EE is still chartered to find a solution and redesign according. That means change.

 

[ptonsparky]

Change creates jobs or guarantees one if you can work things to your advantage.

 

[don_resqcapt19]

The solution at the switch doesn't become less valued just because there's a worse problem somewhere else.
...

I read your statement as saying it would be less likely to have a failure with the factory installed connections in the heater. My experience has been the opposite. I ran a service truck for a few years and did service for electric baseboard heat at a number of appartment units. I repaired a lot more problems with the factory installed parts then I did with the field connections or with the wall mounted line voltage stats.

 

[don_resqcapt19]

I agree. But as we always talk about in the heirarchy of safety design - quit trying to make a safer widget when you can remove the widget entirely. As an industry we should stop trying to make 120V switches and outlets safer. Instead we should be questioning why we have one at all. ...

How would you eliminate 120 volt outlets?

 

[ronaldrc]

I can't imagine that the bare EGC would ever wear though the insulation of another conductor in a residential installation. I expect something else was going on. Maybe an overloaded circuit that heated the wire to the point that it was soft enough that the pressure between the two conductors caused insulation displacement.

I agree if that where so house fires would be a 1000 fold.

 

[weressl]

I can't imagine that the bare EGC would ever wear though the insulation of another conductor in a residential installation. I expect something else was going on. Maybe an overloaded circuit that heated the wire to the point that it was soft enough that the pressure between the two conductors caused insulation displacement.

Quite common occurrence. The heat can also come from the developing high resistance at the screw connection, no overload is necessary. In this case - bare grounding conductor - the time required for the eventual short is even less.

 

[pfalcon]

I read your statement as saying it would be less likely to have a failure with the factory installed connections in the heater. My experience has been the opposite. I ran a service truck for a few years and did service for electric baseboard heat at a number of appartment units. I repaired a lot more problems with the factory installed parts then I did with the field connections or with the wall mounted line voltage stats.

Nothing like cheap equipment to create hazards. And though I agree that running 24V to the switch won't help a factory fix done with superglue ... Well, I haven't seen superglue yet, but I have taken apart some floor heaters and found broken terminals soldered back on - done at the factory. I'd rather the listing agencies enforce standards on the appliances than doing that and also keep designing outlets for idiots.

How would you eliminate 120 volt outlets?

I'm not sure how to replace them all but ... 24V lighting often works better than 120V lighting. I remember 300W lights in our old living room growing up, now they're 55W tops. May even move us to LED instead of CFL. A lot of the receptacle rules are based on providing lights more than anything else. A lot of rooms, such as closets, could be reduced to 24V supply only. But other than contact with appliance faceplates and wall switches, 120/240 is just more efficient for ovens, refrigerators, microwaves, hair dryers ...

 

[kwired]

I agree. But as we always talk about in the heirarchy of safety design - quit trying to make a safer widget when you can remove the widget entirely. As an industry we should stop trying to make 120V switches and outlets safer. Instead we should be questioning why we have one at all.

We are not talking about making a safer widget or removing the widget entirely - we are talking about relocating the widget. With the low voltage control and contactor - you still have a switch making/breaking line voltage, plus you now have more components that can and will fail at some time. It does have its advantages also, many that you have pointed out.

Honestly, because electrical engineers are part of the electrical industry. And because a core part of being an electrical engineer is to design for safety. Houses are burned down because of faulty wiring and it doesn't matter who's to blame. The EE is still chartered to find a solution and redesign according. That means change.

Some engineer was likely involved with the design of the line voltage thermostat on trial here, as well as many products that have and will fail. Failures happen with mechanical equipment. Designing to fail in a safe condition is a good thing but is not always 100% reliable to fail safe.

 

[don_resqcapt19]

In reality our electrical systems are fairly safe. Contrary to what you would think if you read all of the hype for the AFCI rule, less than 10% of the dwelling unit fires are said to be of electrical origin.

 

[kwired]

In reality our electrical systems are fairly safe. Contrary to what you would think if you read all of the hype for the AFCI rule, less than 10% of the dwelling unit fires are said to be of electrical origin.

And of those - how many would have been prevented by an AFCI?

How many are called electrical in nature when they are started by normal heat from an appliance that is being misused?

 

[weressl]

We are not talking about making a safer widget or removing the widget entirely - we are talking about relocating the widget. With the low voltage control and contactor - you still have a switch making/breaking line voltage, plus you now have more components that can and will fail at some time. It does have its advantages also, many that you have pointed out.

Some engineer was likely involved with the design of the line voltage thermostat on trial here, as well as many products that have and will fail. Failures happen with mechanical equipment. Designing to fail in a safe condition is a good thing but is not always 100% reliable to fail safe.

You may also want to address installation negligence when analyzing the potential sources and causes of failure. Contrary to popular beilef held by tradesman not all failures caused by faulty equipment.:lol:

 

[don_resqcapt19]

And of those - how many would have been prevented by an AFCI?

According to statements made by AFCI supporters in the ROPs and ROCs, maybe 40%.

How many are called electrical in nature when they are started by normal heat from an appliance that is being misused?

No one knows and there are a number that are said to be of electrical origin that are not.

 

[hurk27]

In reality our electrical systems are fairly safe. Contrary to what you would think if you read all of the hype for the AFCI rule, less than 10% of the dwelling unit fires are said to be of electrical origin.

I would be willing to bet that a vast majority of electrical fires are caused more of what people plug in rather then the wiring in the walls, not saying it doesn't happen, but most of the ones I been on was over loaded lamp cord extension cords, and damaged cords on appliances, worn out cords, and simply people just not respecting electricity in general.

"Why can't I plug in three electric heaters in this cord ain't that why they put three outlets on it"

 

[brycenesbitt]

I can't imagine that the bare EGC would ever wear though the insulation of another conductor in a residential installation. I expect something else was going on. Maybe an overloaded circuit that heated the wire to the point that it was soft enough that the pressure between the two conductors caused insulation displacement.

How about pushing too hard at install time, followed by slow breakdown of the insulation?
Stiff 12 gauge conductors, small boxes, long tails. I'm always worried I'll break wire nuts.

 

[ptonsparky]

How about pushing too hard at install time, followed by slow breakdown of the insulation?
Stiff 12 gauge conductors, small boxes, long tails. I'm always worried I'll break wire nuts.

That is exactly what it did in the past. Size of boxes and inspectors that looked, have reduced that problem to almost nil. Some of those boxes we used back when electrons were new weren't big enough to put the cable in let alone a device.

 

[pfalcon]

We are not talking about making a safer widget or removing the widget entirely - we are talking about relocating the widget. With the low voltage control and contactor - you still have a switch making/breaking line voltage, plus you now have more components that can and will fail at some time. It does have its advantages also, many that you have pointed out.

Correct, relocating. Effectively the 120V switch remains housed in the main heating unit. Away from normal HO contact, away from normal DIY replacement, and at a single point where protection can be enhanced - inside the heater unit.

Some engineer was likely involved with the design of the line voltage thermostat on trial here, as well as many products that have and will fail. Failures happen with mechanical equipment. Designing to fail in a safe condition is a good thing but is not always 100% reliable to fail safe.

Correct. I simply believe that combining the major failure points into a single location, then working on making that safer, is better than having distributed points of major failure. Progress not perfection.

In reality our electrical systems are fairly safe. Contrary to what you would think if you read all of the hype for the AFCI rule, less than 10% of the dwelling unit fires are said to be of electrical origin.

True from experience. As a landlord we've had two fires attributed to electricity - faulty wiring in a receptacle and faulty wiring in a furnace. Except - in the first case the tenant confessed that they let a 3-yr old play with their lighter who then set the drapes on fire and the receptacle had no damage. Except - in the second case the fire never spread to the furnace room while the waste basket in an adjoining room was the only point below 4' that scorched. So, with my experiences going 0 for 2 I'm betting electrical fires are wildly over estimated.