OT -- switching heating elements

[klem kedidelhopper]

On Jun 19, 12:42 pm, "William Sommerwerck"
<grizzledgee...@comcast.net> wrote:

"Arfa Daily" <arfa.da...@ntlworld.com> wrote in message

news:zXoLp.2426$Zv3.76@newsfe26.ams2...

(The economic "justification" is obvious.)
So what other justification do you think you are looking for?

I guess I'm looking for a groveling "Gee-ee, we're stupid" apology from GE.



It works.  It's perfectly safe until some fool works on it 'live' in the
expectation
that he's going to be safe, and it saves money on the build cost of the
appliance.

As another poster pointed out, there are ovens with both sides switched at
the "bake" selector.

Sorry, but I can only echo Mr Angus's sentiments that working on such
equipment without fully isolating it first, is highly irresponsible,
especially for someone of your usually pedantic persuasion, who I'm sure
would normally be shouting "never assume anything !!" at anyone else who
posted a similar story here ...

Criticism accepted... But in this case I might very well have taken "anyone
else's" side.

Interestingly I also own a GE stove and coincidentally my bake element
developed a hot spot one day and "exploded" open and also needed to be
replaced. I never even thought of the possibility that only one side
of the 240 was being switched off from the control unit when I
replaced it, Like you William I just would have expected such a design
to be both impractical as well as unsafe. However I did unplug the
stove first, but just purely from habit, ( and because I really don't
like working on live circuits, unless there is no other alternative).
So in all honesty I made the same assumption that you did with the
exception that my stove was unplugged.
The model number of my stove is JBP64 and it is almost ten years old.
GE was nice enough to provide a service page with their appliances,
(at least they were still doing it at the time we purchased this
model), and it included a schematic. I just looked at it and
incredible as it may seem, sure enough L2 is directly connected to one
side of both the bake and broil elements!
I've never forgotten the words of one of my teachers many years ago
when I was in electronics school. He never seemed to tire of reminding
us to "never assume that the power is off". And I try very hard not
to. Good advice when you run into something unexpected like this. Lenny

 

On Sat, 18 Jun 2011 17:57:14 -0700, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

I just had to replace the bottom element in my GE oven, and discovered -- to
my great surprise -- that one side of the element is always "hot" -- that
is, it has voltage on it. I will be calling Appliance Park next week and
verbally tearing someone a new oven cavity.

Is this normal? And if it is, is it for some reason other than saving money?
That is common. The resistance element is encapsulated in a

protective sheath. You cannot remove the heating element without
removing the back of the appliance. I would wager the appliance was
shipped with a warning label indicating it should be removed only by
qualified servicers.

Also, recall if either a mechanical or solid state double pole relay
were used, one side could fail (contacts welded or SCR shorted) and
you would never know the difference.

There are titles for those who work on appliances without first
ensuring it is disconnected. "The Dear Departed" is one. "Candidate
for a Darwin Award" is another. I prefer 'Fool".

PlainBill

 

[William Sommerwerck]

<PlainBill@yawhoo.com> wrote in message
news:6tmsv6t6b0f46pn2ufmhj3mnokpskrb765@4ax.com...

On Sat, 18 Jun 2011 17:57:14 -0700, "William Sommerwerck"
grizzledgeezer@comcast.net> wrote:

I just had to replace the bottom element in my GE oven, and discovered --
to
my great surprise -- that one side of the element is always "hot" -- that
is, it has voltage on it. I will be calling Appliance Park next week and
verbally tearing someone a new oven cavity.

Is this normal? And if it is, is it for some reason other than saving
money?

That is common. The resistance element is encapsulated in a
protective sheath. You cannot remove the heating element without
removing the back of the appliance. I would wager the appliance was
shipped with a warning label indicating it should be removed only by
qualified servicers.

You don't have to take off the back of the oven. You can remove the element
in situ. Just undo two 1/4" hex-head screws, pull out the base of the
element a bit, and pull off the friction-fit connectors.

 

[William Sommerwerck]

"klem kedidelhopper" <captainvideo462009@gmail.com> wrote in message
news:c57a5c52-9fa3-44b0-9d97-2d4c08bf27f6@dq9g2000vbb.googlegroups.com...

You don't have to take off the back of the oven. You can remove the
element in situ. Just undo two 1/4" hex-head screws, pull out the base
of the element a bit, and pull off the friction-fit connectors.

Well at least one side of the line is disconnected.

If both sides were connected, the element would be on! Wouldn't it?

Thank God for small favors. So when you reach inside the oven
and pull the hot terminal off the element while you're leaning on
the open door with your chest, you only pass 120 through you heart.

Well, I was clothed. And the door was off.

 

[William Sommerwerck]

"Ron D." <ron.dozier@gmail.com> wrote in message
news:934e1a22-dd8b-414f-8208-86bdbd6f3b28@a10g2000vbz.googlegroups.com...

Triac controlled heaters would only switch one side. The disconnect
is responsible for switching both.

I've only seen one piece of industrial equipment that had a breaker
in the neutral. Basically 3 huge HIGH POWER like 15 kW*3 picture
tube like power supplies BUT VERY HIGH POWER. 15 kV at 3 amps.

The system required 70 Amp 3 phase 208 VAC to operate. Blink and
you're dead. Keys are required to get passed the access doors on the
equipment.

For those who enjoy calling me an idiot... I used to service klystrons with
20kV anode supplies. One was vehwy, vehwy kehful around these. You not only
made sure the power was off, but you used a conductive pole to short the
supply.

 

[klem kedidelhopper]

On Jun 19, 4:54 pm, "William Sommerwerck" <grizzledgee...@comcast.net>
wrote:

PlainB...@yawhoo.com> wrote in message

news:6tmsv6t6b0f46pn2ufmhj3mnokpskrb765@4ax.com...



On Sat, 18 Jun 2011 17:57:14 -0700, "William Sommerwerck"
grizzledgee...@comcast.net> wrote:
I just had to replace the bottom element in my GE oven, and discovered --
to
my great surprise -- that one side of the element is always "hot" -- that
is, it has voltage on it. I will be calling Appliance Park next week and
verbally tearing someone a new oven cavity.
Is this normal? And if it is, is it for some reason other than saving

money?

That is common. The resistance element is encapsulated in a
protective sheath. You cannot remove the heating element without
removing the back of the appliance. I would wager the appliance was
shipped with a warning label indicating it should be removed only by
qualified servicers.

You don't have to take off the back of the oven. You can remove the element
in situ. Just undo two 1/4" hex-head screws, pull out the base of the
element a bit, and pull off the friction-fit connectors.

Well at least one side of the line is disconnected. Thank God for
small favors. So when you reach inside the oven and pull the hot
terminal off the element while you're leaning on the open door with
your chest, you only pass 120 through you heart....... Lenny

 

[Ron D.]

Triac controlled heaters would only switch one side. The disconnect
is responsible for switching both.

I've only seen one piece of industrial equipment that had a breaker
in the neutral. Basically 3 huge HIGH POWER like 15 kW*3 picture
tube like power supplies BUT VERY HIGH POWER. 15 kV at 3 amps.

The system required 70 Amp 3 phase 208 VAC to operate. Blink and your
dead. Keys are required to get passed the access doors on the
equipment.

 

[Sylvia Else]

On 20/06/2011 12:52 AM, nesesu wrote:

On Jun 18, 8:42 pm, Sylvia Else<syl...@not.here.invalid> wrote:
On 19/06/2011 1:20 PM, William Sommerwerck wrote:

I should have explained that I went to remove the element without
opening the breaker -- on the assumption that no engineer in his
right mind would leave one side of the heating element powered.

Are you stupid? NOTHING gets worked on while connected to power.

"Foolish" might be more apt than "stupid". And people commonly work on
powered TVs and other electronic equipment -- with proper precautions, of
course.

We still need an answer to the original question... Why?

I think it's perfectly normal for appliances to switch only one pole of
the power supply, that pole being the live one. Same with power points
and light switches. I don't think I've seen an appliance with a double
power power switch.

What's not normal, and dangerous, is for the neutral wire to be the one
switched. Either the oven is miswired internally, is miswired to the
mains supply, or the mains supply is miswired. Whichever it is needs to
be fixed.

Sylvia.

We are talking at cross purposes here. In the UK and Australia, the
240V has one side neutral and the other 'hot' while in North America
the 240V is both sides hot and centre neutral. In my stove the oven
thermostat is the typical single pole switch in one side of the
element circuit, but both sides pass through the 'oven function'
selector switch that offers 'OFF', 'Bake', 'Broil' and 'Clean'. When
that switch is OFF then the element is dsconnected from both hot
feeds.
In Canada, a heating thermostat for controlling 240V space heaters
[permanently connected] may be a single pole type, but if it has an
'OFF' position marked, it MUST open both circuits.

Neil S.

It's true that I had overlooked the strange approach to supplying
domestic power in North America.

One possibility that the OP needs to address is that the switch is
simply broken, or has one pole bridged by a wire.

But either way, I hold with the consensus here - you don't start taking
appliances apart while any part of them is powered, which includes their
switches. (But pleads guilty to removing and installing boards on PCs
while they're on standby!).

Sylvia.

 

[spamtrap1888]

On Jun 19, 5:14 pm, "William Sommerwerck" <grizzledgee...@comcast.net>
wrote:

"klem kedidelhopper" <captainvideo462...@gmail.com> wrote in message

news:c57a5c52-9fa3-44b0-9d97-2d4c08bf27f6@dq9g2000vbb.googlegroups.com...

You don't have to take off the back of the oven. You can remove the
element in situ. Just undo two 1/4" hex-head screws, pull out the base
of the element a bit, and pull off the friction-fit connectors.
Well at least one side of the line is disconnected.

If both sides were connected, the element would be on! Wouldn't it?

But you wouldn't be replacing the element if it was on, right?

 

[William Sommerwerck]

"spamtrap1888" <spamtrap1888@gmail.com> wrote in message
news:46d71b8a-ea16-41d8-b274-219d03f80a3e@22g2000prx.googlegroups.com...
On Jun 19, 5:14 pm, "William Sommerwerck" <grizzledgee...@comcast.net>
wrote:

"klem kedidelhopper" <captainvideo462...@gmail.com> wrote in message
news:c57a5c52-9fa3-44b0-9d97-2d4c08bf27f6@dq9g2000vbb.googlegroups.com...

You don't have to take off the back of the oven. You can remove the
element in situ. Just undo two 1/4" hex-head screws, pull out the base
of the element a bit, and pull off the friction-fit connectors.

Well, at least one side of the line is disconnected.

If both sides were connected, the element would be on! Wouldn't it?

But you wouldn't be replacing the element if it was on, right?

Correct. But you said "Well, at least one side of the line is disconnected".

 

[William Sommerwerck]

"klem kedidelhopper" <captainvideo462009@gmail.com> wrote in message
news:87dc74d5-a347-4fc4-bf8e-3950d6044d43@a31g2000vbt.googlegroups.com...

Someone is saving a buck. There must be money involved somehow.
It's the least common denominator. It always is.

As someone said... "Don't assume conspiracies when simple stupidity is
enough to explain something."

 

[Jeffrey Angus]

On 6/20/2011 8:10 AM, William Sommerwerck wrote:

"klem kedidelhopper"<captainvideo462009@gmail.com> wrote in message
news:87dc74d5-a347-4fc4-bf8e-3950d6044d43@a31g2000vbt.googlegroups.com...

Someone is saving a buck. There must be money involved somehow.
It's the least common denominator. It always is.

As someone said... "Don't assume conspiracies when simple stupidity is
enough to explain something."

It's a series circuit, it only take ONE switch to open it.
There is absolutely NO reason to use a dual pole switch.

I'm tired of hearing "It's the evil corporations" being at fault
for people that can't or won't pay attention when doing their
own repairs and try to shift the blame from their own carelessness.

Jeff


--
"Everything from Crackers to Coffins"

 

[Smitty Two]

In article <itngtl$goc$1@dont-email.me>,
"William Sommerwerck" <grizzledgeezer@comcast.net> wrote:

As someone said... "Don't assume conspiracies when simple stupidity is
enough to explain something."

I thought you were going to drop this thread, but since your words and
actions don't match, I'll agree with others who've opined that you're
the stupid one here, working on a 240 volt system with it plugged in.

 

[klem kedidelhopper]

On Jun 19, 8:14 pm, "William Sommerwerck" <grizzledgee...@comcast.net>
wrote:

"klem kedidelhopper" <captainvideo462...@gmail.com> wrote in message

news:c57a5c52-9fa3-44b0-9d97-2d4c08bf27f6@dq9g2000vbb.googlegroups.com...

You don't have to take off the back of the oven. You can remove the
element in situ. Just undo two 1/4" hex-head screws, pull out the base
of the element a bit, and pull off the friction-fit connectors.
Well at least one side of the line is disconnected.

If both sides were connected, the element would be on! Wouldn't it?

Thank God for small favors. So when you reach inside the oven
and pull the hot terminal off the element while you're leaning on
the open door with your chest, you only pass 120 through you heart.

Well, I was clothed. And the door was off.

Someone is saving a buck. There must be money involved somehow. It's
the least common denominator. It always is.
Lenny

 

[William Sommerwerck]

"Jeffrey Angus" <jangus@suddenlink.net> wrote in message
news:itnlgj$hhu$1@dont-email.me...

On 6/20/2011 8:10 AM, William Sommerwerck wrote:
"klem kedidelhopper"<captainvideo462009@gmail.com> wrote in message

news:87dc74d5-a347-4fc4-bf8e-3950d6044d43@a31g2000vbt.googlegroups.com...

Someone is saving a buck. There must be money involved somehow.
It's the least common denominator. It always is.

As someone said... "Don't assume conspiracies when simple stupidity is
enough to explain something."

It's a series circuit, it only take ONE switch to open it.
There is absolutely NO reason to use a dual pole switch.

I'm sorry, but you're wrong -- probably because you aren't familiar with
American wiring.

The standard line voltage in North America is 120V (or thereabouts). Most
houses are wired to two "phases" (or whatever the correct term is). When
higher voltage is needed -- for a dryer, range, or water heater -- the
device is connected across these phases, producing a net voltage of around
210V.

Now, if you connect /either/ of these phases to the neutral, current will
flow. This is what happened when I moved the element -- it banged into the
neutral (the oven wall itself, presumably), and tripped the breaker.

As someone else pointed out, my range and other GE ranges have one side of
the baking and broiling elements permanently connected to one of the phases,
making them /live/ as long as the breaker is connected. There is no reason
for this, other than saving a dollar or two manufacturing costs.

I'm tired of hearing "It's the evil corporations" being at fault
for people that can't or won't pay attention when doing their
own repairs and try to shift the blame from their own carelessness.

I spoke with a customer-service rep at GE this morning, who agreed that
switching only one side of the line was potentially (pun intended?)
dangerous. Think of an oven in a flooded basement.

 

[William Sommerwerck]

"Smitty Two" <prestwhich@earthlink.net> wrote in message
newsrestwhich-8F3795.07383820062011@news.eternal-september.org...

In article <itngtl$goc$1@dont-email.me>,
"William Sommerwerck" <grizzledgeezer@comcast.net> wrote:

As someone said... "Don't assume conspiracies when simple stupidity is
enough to explain something."

I thought you were going to drop this thread, but since your words and
actions don't match, I'll agree with others who've opined that you're
the stupid one here, working on a 240 volt system with it plugged in.

I was, but people kept responding.

 

[Jeffrey Angus]

On 6/20/2011 11:43 AM, William Sommerwerck wrote:

"Jeffrey Angus"<jangus@suddenlink.net> wrote in message

It's a series circuit, it only take ONE switch to open it.
There is absolutely NO reason to use a dual pole switch.

I'm sorry, but you're wrong -- probably because you aren't familiar with
American wiring.

The standard line voltage in North America is 120V (or thereabouts). Most
houses are wired to two "phases" (or whatever the correct term is). When
higher voltage is needed -- for a dryer, range, or water heater -- the
device is connected across these phases, producing a net voltage of around
210V.

Now, if you connect /either/ of these phases to the neutral, current will
flow. This is what happened when I moved the element -- it banged into the
neutral (the oven wall itself, presumably), and tripped the breaker.

As someone else pointed out, my range and other GE ranges have one side of
the baking and broiling elements permanently connected to one of the phases,
making them /live/ as long as the breaker is connected. There is no reason
for this, other than saving a dollar or two manufacturing costs.

And in short (pun intended) you were using it wrong.
Under normal operation there is absolutely no reason what so ever
for one or the other side to go to neutral.

I'm tired of hearing "It's the evil corporations" being at fault
for people that can't or won't pay attention when doing their
own repairs and try to shift the blame from their own carelessness.

I spoke with a customer-service rep at GE this morning, who agreed that
switching only one side of the line was potentially (pun intended?)
dangerous. Think of an oven in a flooded basement.

The cabinet is supposed to be grounded.

This isn't like the classic "All the wiring is floating" toaster in the
bath tub trick.

And if you're foolish enough to try using an electrical oven (or any
other electrical appliance) in a flooded basement, you deserve anything
that happens to you.

Jeff


--
"Everything from Crackers to Coffins"

 

[Jeffrey Angus]

By the way, on page 3 of the users manual for the GE JBP64
it makes a couple of interesting statements.

1. Make sure you appliance is properly installed and GROUNDED.
2. Before performing any service, disconnect the range power
supply at the household distribution panel by removing the
fuse or switching off the circuit breaker.

But what I find really interesting...

"Do not attempt to repair or replace any part of your range
unless is specifically recommended in the manual. All other
servicing should be referred to a qualified technician."

The user manual goes on to tell you how to clean it, and how
to change the light bulb in the oven. NOWHERE does it tell you
to replace the burner elements.

So which part of the manual did you think did not apply to
you?

Well, William, wanna give it another go at how you're the
victim here of a corporation's greed?

Remember, it ONLY takes ONE switch to OPEN a series circuit.
That is ALL that is required to control whether or not the
element gets hot or cools off.

Oh and by the way, since you brought it up, the bit about
both of the 240 volt sources being "hot with respect to
neutral". The heating elements are connected ACROSS the 240
VAC source, NOT split with each half going from the two
sources to neutral. (That would require a double contact to
turn each PAIR of heating elements on and off.)

"Removing power" on the other hand is accomplished, per the
manual, by turning off the source. (And yes, that turns off
BOTH sides of the 240 VAC supply.)

Jeff

--
"Everything from Crackers to Coffins"

 

[William Sommerwerck]

"Jeffrey Angus"<jangus@suddenlink.net> wrote in message

The cabinet is supposed to be grounded. This isn't like the classic
"All the wiring is floating" toaster in the bath tub trick.

I'm not sure about that. I think there is a similarity. "Mythbusters" showed
that someone /can/ be electrocuted when a heater or toaster is tossed into a
bathtub.

And if you're foolish enough to try using an electrical oven (or any other
electrical appliance) in a flooded basement, you deserve anything that
happens to you.

Of course! But what would happen if someone waded into the flooded basement
to shut off the breakers (which is what I was thinking of)? If the water
were high enough to enter the oven cavity, the water would be "hot".

I agree that no one should enter a flooded room without wearing waterproof
rubber boots, but... Many possible accidents -- however unlikely -- are
/predictable/. Why not avoid them in the first place, especially when it
adds next to nothing to the cost of the appliance?

Many years ago, my father was using a metal-bodied electric drill in the
basement. He was wearing leather-soled shoes and standing on concrete, which
(as it is in many basements) was faintly damp. The drill's motor shorted out
to the metal body, and he was nearly electrocuted. This was before
double-insulated tools, and outside of not standing on a thick rubber mat, *
he was doing nothing wrong. At least, not by the standards of the day.

In the US, new construction requires GFI outlets near sinks or other water
supplies.

* Black rubber objects often contain carbon, which is more conductive than
you might think. I discovered this more than 30 years ago when trying to use
rubber washers to insulate rack-mount equipment.

 

[William Sommerwerck]

"Jeffrey Angus" <jangus@suddenlink.net> wrote in message
news:itom8d$233$1@dont-email.me...

By the way, on page 3 of the users manual for the GE JBP64
it makes a couple of interesting statements.

1. Make sure you appliance is properly installed and GROUNDED.
2. Before performing any service, disconnect the range power
supply at the household distribution panel by removing the
fuse or switching off the circuit breaker.

But what I find really interesting...
"Do not attempt to repair or replace any part of your range
unless is specifically recommended in the manual. All other
servicing should be referred to a qualified technician."

I am an qualified technician -- despite what you might think.

Well, William, wanna give it another go at how you're the
victim here of a corporation's greed?

I'm not anybody's victim.

Remember, it ONLY takes ONE switch to OPEN a series circuit.
That is ALL that is required to control whether or not the
element gets hot or cools off.

You were not paying attention! Any heating device that uses both "phases"
requres TWO switches to open it.

Oh, and by the way, since you brought it up, the bit about
both of the 240 volt sources being "hot with respect to
neutral". The heating elements are connected ACROSS the 240
VAC source, NOT split with each half going from the two
sources to neutral. (That would require a double contact to
turn each PAIR of heating elements on and off.)

I'm not sure what you're talking about. First, there is no "240V" source in
my condo. There are multiple 120V sources from which you can get higher
voltages by spanning them. (I assume each voltage is referenced to some
"neutral" point.) In my preceding apartment, I took advantage of this to
build a break-out box -- all to code, I have several electrician friends who
advised me -- to provide individual lines for my class A power amps.

As someone else kindly pointed out, this oven has one side of its elements
hard-wired to AC. Bad, bad, bad, bad idea.