Immersion heater - no ground?

[jmw]

I have some need to make small amounts of heated cleaning solutions in a location with power but no hot water tap, and eventually found these searching around. Are these heating elements as sketchy as they look? There is no grounded plug, I'm guessing it is coiled nichrome wire inside that's surrounded by ceramic, and hopefully there's a fuse in there. So the outside coil is either floating or bonded to neutral, and if the nichrome ever wiggles enough to touch it, the coil surface becomes electrically live in a conductive fluid. Am I right or is it actually possible to use these safely?

[DannyTheGhost]

This type of heater is the main reason why we here are prohibited from using any water heaters - even electrical kettles - in ANY type of building except private house (which of course will not save us from people who dont care about it or cant care - when there's no money to buy anything more safe).
No fuses, no protection, nothing - all safety is "get lucky enough to not forget about it or your house will burn down".
It is simple as that - just pure resistive load that heats itself with plastic handle that melts quite quickly if you don't put it in water or put it for too long.

[David Hess]

So the outside coil is either floating or bonded to neutral, and if the nichrome ever wiggles enough to touch it, the coil surface becomes electrically live in a conductive fluid. Am I right or is it actually possible to use these safely?

The outside envelope is floating but I have never heard of them failing unless abused.  They can always be used with a ground fault interrupter.

[Haenk]

These were very common until not too long ago, I think my parents still have one of those for caravaning and travelling. Usually they are pretty safe to use (I don't think the metal part is connected at all); the heating element inside is insulated.

Now *this* one is another story:



Possible death included as a free addon

[Yansi]

We have also one of these, old ones. But it HAS a ground pin and a three wire cable attached to it.

[amyk]

Use with an insulated container, or a grounded one and a GFI outlet.

[CaptDon]

Used to use these to reheat a cold cup of coffee
or heat water to make instant coffee. You folks do
realize that with a two pin connector the average
GFI cannot pick up the type of lethal fault this thing
can produce. The fault current path is not through
the receptacle ground. The only GFI that can pick up
this fault is one that measures differential current
flow between line and neutral. Some only sense
current coming back (or going out) the ground pin.
I had a sound job on an outdoor gig and the GFI
kept tripping. I had a ground rod as a safety ground
on my end. Their building ground had about 1vac
on it and was flowing current 'out' to my safety ground
and tripping their GFI. I used ground lift on their end
and relied on my safety ground at my end!!
 

[David Hess]

I have never seen a GFI which made any use of its ground connection.  They just pass it through.  Detecting the ground current would defeat the purpose of the GFI.

Internally they use a current transformer to detect the *difference* in current between hot and neutral which indicates a common mode current.  That current can be to ground or anything else including another neutral or hot so they work fine with two wire devices.

[langwadt]

I have never seen a GFI which made any use of its ground connection.  They just pass it through.  Detecting the ground current would defeat the purpose of the GFI.

Internally they use a current transformer to detect the *difference* in current between hot and neutral which indicates a common mode current.  That current can be to ground or anything else including another neutral or hot so they work fine with two wire devices.

sure, so with a three wire device with chassis grounded the gfi trips if there is a short to chassis, with a two wire device with a short to chassis the gfi trips when you touch the chassis

though a device with out ground will usually (always?) be classII double insulated 

[Ultrapurple]

I have a 12V heater like this that I keep in the car - that isn't grounded either 

[AVGresponding]

I have a 12V heater like this that I keep in the car - that isn't grounded either 

Probably best not to use it to warm your hands on a cold day then!

[themadhippy]

I have never seen a GFI which made any use of its ground connection

In the uk at least there was a voltage operated device that monitored the voltage to earth ,they sort of worked,but had a few drawbacks that made them a bit dodgy  and so are no longer permitted in our regs

[jh15]

In the States, code would require your rod be bonded to theirs.

[CaptDon]

I liked the setup in the hospital O.R.'s. We had a completely isolated
120vac supply. Each room had its own 5kva transformer with a LEM
device to sense the center point of 60-0-60 shifting. I think there was
around 5meg of resistance from the center tap to earth ground and they
measured shift against earth ground to detect upsets or patient
body current. The LEM's got a little pissy when we were using the E.S.U.'s
(Electro Surgical Units).You could firmly grasp ground and either side
of the line (But not both at once of course) and not get shocked. Also,
all of our outlets were against N.E.C. regulations and were mounted
with ground facing up. This was done so the metal catheter wires would
hit ground rather than hot if they dragged over an outlet. Of course with
an ungrounded isolated supply it should not have mattered if they did
hit the hot line.

[Ultrapurple]

mounted with ground facing up. This was done so the metal catheter wires would
hit ground rather than hot if they dragged over an outlet

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