Immersion heater - no ground? - Page 1
Forum section: electronics / general

author: jmw
author_rank: Frequent Contributor
timestamp: May 19, 2020, 08:16:43 am
content: 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?

author: DannyTheGhost
author_rank: Contributor
timestamp: May 19, 2020, 09:39:18 am
content: 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.

author: David Hess
author_rank: Super Contributor
timestamp: May 19, 2020, 01:55:47 pm
content: Quote from: jmw on May 19, 2020, 08:16:43 amThe outside envelope is floating but I have never heard of them failing unless abused. They can always be used with a ground fault interrupter.

author: Haenk
author_rank: Super Contributor
timestamp: May 19, 2020, 06:51:33 pm
content: 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

author: Yansi
author_rank: Super Contributor
timestamp: May 19, 2020, 07:26:09 pm
content: We have also one of these, old ones. But it HAS a ground pin and a three wire cable attached to it.

author: amyk
author_rank: Super Contributor
timestamp: May 21, 2020, 12:11:01 am
content: Use with an insulated container, or a grounded one and a GFI outlet.

author: CaptDon
author_rank: Super Contributor
timestamp: June 08, 2020, 05:44:57 pm
content: Used to use these to reheat a cold cup of coffeeor heat water to make instant coffee. You folks dorealize that with a two pin connector the averageGFI cannot pick up the type of lethal fault this thingcan produce. The fault current path is not throughthe receptacle ground. The only GFI that can pick upthis fault is one that measures differential currentflow between line and neutral. Some only sensecurrent coming back (or going out) the ground pin.I had a sound job on an outdoor gig and the GFIkept tripping. I had a ground rod as a safety groundon my end. Their building ground had about 1vacon it and was flowing current 'out' to my safety groundand tripping their GFI. I used ground lift on their endand relied on my safety ground at my end!!

author: David Hess
author_rank: Super Contributor
timestamp: June 08, 2020, 07:00:12 pm
content: 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.

author: langwadt
author_rank: Super Contributor
timestamp: June 08, 2020, 08:06:23 pm
content: Quote from: David Hess on June 08, 2020, 07:00:12 pmsure, 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 chassisthough a device with out ground will usually (always?) be classII double insulated

author: Ultrapurple
author_rank: Super Contributor
timestamp: June 09, 2020, 08:46:16 am
content: I have a 12V heater like this that I keep in the car - that isn't grounded either

author: AVGresponding
author_rank: Super Contributor
timestamp: June 09, 2020, 06:40:13 pm
content: Quote from: Ultrapurple on June 09, 2020, 08:46:16 amProbably best not to use it to warm your hands on a cold day then!

author: themadhippy
author_rank: Super Contributor
timestamp: June 09, 2020, 07:28:29 pm
content: QuoteIn 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

author: jh15
author_rank: Frequent Contributor
timestamp: June 09, 2020, 07:33:59 pm
content: In the States, code would require your rod be bonded to theirs.

author: CaptDon
author_rank: Super Contributor
timestamp: June 09, 2020, 08:48:00 pm
content: I liked the setup in the hospital O.R.'s. We had a completely isolated120vac supply. Each room had its own 5kva transformer with a LEMdevice to sense the center point of 60-0-60 shifting. I think there wasaround 5meg of resistance from the center tap to earth ground and theymeasured shift against earth ground to detect upsets or patientbody 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 sideof 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 mountedwith ground facing up. This was done so the metal catheter wires wouldhit ground rather than hot if they dragged over an outlet. Of course withan ungrounded isolated supply it should not have mattered if they didhit the hot line.

author: Ultrapurple
author_rank: Super Contributor
timestamp: June 11, 2020, 09:50:34 am
content: Quote from: CaptDon on June 09, 2020, 08:48:00 pmOuch ... Ouch ... Ouch ... Ouch ... Ouch ...