"ESD Safe" soldering iron ungrounded--is that CE certifiable?

[Skyfox]

Hi all,

A few weeks ago I bought one of those cheap Chinese Hakko lookalike soldering irons for $30 on eBay.  It's the Zeny 937D+ soldering station and functionally the thing works just fine with its digital LED temperature display and fairly fast heating.  However, when I was first checking it out I noticed there was no continuity between the iron's tip and the ground pin on the wall plug.  I popped the lid off and this is what it looks like.



Notice there are only two pairs of wires:  one for the control board and one for the soldering iron power.  The ground wire from the mains cable is anchored on the transformer mounting screw.  Here's a look at the back of the board:



Outlined in yellow is the ground pin coming in from the soldering iron plug.  I have continuity between this point and the soldering iron tip.  See anything missing?  The freakin' ground wire that should be attached where that blob of solder is!  Here's a look at the underside of the board where the components are:



Circled in yellow is the area where that blob of solder sits in the little ground plane of that ground pin.  Clearly there's nothing attached to that ground connection from this side of the board.

Anyway, I called out the seller for false advertisement since the sale page said "ESD Safe", the box it came in (for the 936 model...they couldn't even be bothered to sell it in the correct box) says "ESD Safe", and the front of the unit is stamped "ESD Safe".  The way they replied to me practically sounded like "that's how it's supposed to be".  I told them this would never pass certification by CE, UL, or anything else.  They responded claiming that it is indeed CE certified, and attached a copy of their CE certification for this and dozens of other soldering station models.  However, nowhere on the soldering station unit itself, in the manual, or on the box is it stamped CE or any other label for a certification agency.

But my question to you all is, would an ungrounded soldering station, especially one claiming to be ESD safe with its labeling, actually pass CE certification?  Or is their CE certificate they sent me just another example of blowing smoke out of some bodily orifice?  By the way, I've already fixed the problem by installing my own ground wire.

[chris_leyson]

I think the CE mark covers electrical safety and not ESD. From a safety point of view the transformer is earthed and double insulated. Maybe connect a 1M ohm from the ground pin on the irons socket to earth, that will give some ESD protection.

[chris_leyson]

I just checked my Pace ST75 and the iron is connected directly to earth, so maybe forget the 1M ohm resistor and wire the ground pin on the socket directly to earth.

[Ian.M]

The issue is leakage current from the hot element to the element sheath.  This makes it *DIFFICULT* to reliably ground the bit through a resistor to control ESD as there is always *SOME* AC leakage through the transformer inter-winding capacitance.  One approach would be a 'humdinger' pot across the secondary that powers the element with its wiper AC grounded via a large low leakage capacitor, adjusted for minimum AC voltage across the 1M resistor.   A better approach would be a double insulated heater, with a properly grounded screen between the two layers of insulation, but AFAIK no-one makes that.

As-is, with a hard-earthed bit on your iron, if a board has anything that can store enough charge to matter, one *MUST* remove all external connections before soldering anything.  You will learn this the hard way^* some day when working with a MCU with battery or supercap backup . . . . . 

* Which is why I now favour an ESD safe gas iron!

[Gyro]

As the AC is Triac switched it's likely to be rather spiky. My preference would be a resistive ground connection to the tip too but in practice it might let through too much spike voltage. Maybe you could scope the tip with different value grounding resistors.

I suppose having a solid grounded tip is actually safer (you'd know as soon as it touched a live circuit) rather than being blissfully unaware until you apply the solder! 

[GEuser]

https://en.wikipedia.org/wiki/CE_marking , i could not make heads or tails out of that stuff .

Good that you checked though , i think it's a mandatory thing to do these days no matter what or who makes , also before the blue wires plug(actual) it looks like they were soldered onto the board via the 2 extra pads there .

My new iron has a tip earth direct to mains earth btw .

edited> actually i could not recall seeing the transformer earthed in mine so just took a look and nope , next time I'm at the bench I'll earth it out (it looks like they just forgot to add a wire in yours?)
https://www.eevblog.com/forum/reviews/atten-at980-soldering-iron-(peek-inside)/

[Skyfox]

Those two large solder pads next to the blue wire plug don't go to anything either.  I really don't know why they're there.  Maybe they forgot to add a wire at the manufacturing plant, which is a possibility, but the seller shouldn't be defending such an error as how it's supposed to be.  I realize the thing is cheap, and actually for $30 it's really not bad at all, but they shouldn't be lying about the grounding safety of their product.

Quote from: GEuser on Today at 10:26:33 AM>https://en.wikipedia.org/wiki/CE_marking , i could not make heads or tails out of that stuff .

Good that you checked though , i think it's a mandatory thing to do these days no matter what or who makes , also before the blue wires plug(actual) it looks like they were soldered onto the board via the 2 extra pads there .

My new iron has a tip earth direct to mains earth btw .

edited> actually i could not recall seeing the transformer earthed in mine so just took a look and nope , next time I'm at the bench I'll earth it out (it looks like they just forgot to add a wire in yours?)
https://www.eevblog.com/forum/reviews/atten-at980-soldering-iron-(peek-inside)/

[GEuser]

Those two large solder pads next to the blue wire plug don't go to anything either.  I really don't know why they're there.

They must be for the 2 blue wires (before they had a plug there) is what i was trying to imply , so before they came up with the idea of a plug they had the 2 solder pads i guess ..

[saturation]

CE is self 'certification' that the manufacturer complies with laws for electronic safety, maybe EMC, etc., required for sale of such devices in the EU, its not required for sale in the USA.  In the EU it effectively useless as its rarely enforced or checked, CE issues are discussed elsewhere on the forums at length.

In the USA safety issues for consumer products are covered by CPSA and OSHA for professional use, but either will only act if a complaint is filed or an incident occurs as a result of the device.  The same is with the FCC in regards to EMC for anything sold in the USA, a complaint of emissions must first be filed.

ESD is usually checked with NRTL certification, but its not a user safety issue.

CE more should mean "Caveat Emptor".

[KL27x]

I don't see how that is a safety issue. If it doesn't blow up FETs or laser diodes, it's ESD safe. Measure the ripple current on it with your scope? 

[GEuser]

CE more should mean "Caveat Emptor".

Ha Ha , good one .

Can i put you on the "spot" btw , it looks like you might be the person to ask as i was dwelling on this for a while and was hoping it'd come up somewhere , so far it has not .

RE> Conformity of color coded wires internal to a device , (Mains AC) , , , Brown active , Blue neutral , Green/yellow earth supposedly the common codes out here at least and maybe in other places , do you know if those same codes have to be used or are supposedly law to be used internal to a device? , i assume not as as we all know there are reds/yellows/whites/greens/blacks excetera off the inner sockets heading off internally , or is it just a common practice even if there is a code?

Or is it a , the consumer should not be inside said device so therefore it does not matter .

edited> add link> https://en.wikipedia.org/wiki/Electrical_wiring

[saturation]

As I recall, there are no color coding laws inside electronic devices at least in the USA, but there are international standards for color coding: wiring for autos, computers etc.,.  Where a device interfaces to the electrical system [mains], color codes become mandated if the colors are visible; e.g. if you install a light fixture directly connected to mains not via a plug.  Many device have no exposed wires but terminals where an electrician must wire the device to mains using color codes, and other things like gauges and right size terminal bolts, to your local code.

There are many electrical codes internationally that are essentially law as they are enforced by government, because there is a safety issue associated with the codes.   

If an appliance is mis-made, where miswired is part of it, then that is a consumer protection issue enforced in the USA by the attorney general of each state.

Most codes require electrical device to have safety certification, like UL, ETL, etc., the NRTL groups in the USA, these NRTL labs enforce the international standard wiring conventions to the maker in order to have the safety 'mark'.

So, CE is truly caveat emptor 

Now that said, a few responsible manufacturers resort to CE only in some markets to save development cost because they know a 3rd party safety certification or listing is not needed for sale in that region, and they know internally their devices conform to all safety and codes if required, so if they choose to resell it in another country and get certified, it will pass without problems.

For example, Fluke sells DMMs in China that are only CE but for sale only in countries were CE alone is acceptable.  Many Japanese makers like Yogokawa, Hioki, Sanwa, do the same.  Taiwan makers do so too, GWInstek, Pintek etc.,

FWIW a safety mark cost about $5000-$30,000 per device to get approval and thereafter, $2,000-3,000 per device annually to remain listed.  Price varies with the complexity of the device and the agency, UL being the first and most expensive. 
 

CE more should mean "Caveat Emptor".

Ha Ha , good one .

edited> add link> https://en.wikipedia.org/wiki/Electrical_wiring

[madires]

I think the CE mark covers electrical safety and not ESD. From a safety point of view the transformer is earthed and double insulated. Maybe connect a 1M ohm from the ground pin on the irons socket to earth, that will give some ESD protection.

Yup, it's a class II device. So, from a safety standpoint of view it would comply with CE. The "ESD safe" is just a feature which isn't delivered as promised. Since there's a PE terminal the OP should simply crimp a ring terminal to a proper wire, add it it to the PE terminal and solder the other end to the PCB. For $30 I would expect such minor issues. 

[GEuser]

@saturation , Thanks for the trouble to type that up , newcomers to the Hobby should be very aware to the symptom of the colors of wires inside devices being non-conformal and as a lot have already found out even the way things are wired up should be checked and double checked every-time no matter what .

And as proven from just a while back even Electrical leads should be given a quick check-over (unplugged both ends of course).

Out of the heaps and heaps of stuff i have peeked inside a lot of the big brand name stuff had color coded mains wires in the device's (inside) , from years ago of course .

[SteveyG]

I think the CE mark covers electrical safety and not ESD. From a safety point of view the transformer is earthed and double insulated. Maybe connect a 1M ohm from the ground pin on the irons socket to earth, that will give some ESD protection.

Yup, it's a class II device. So, from a safety standpoint of view it would comply with CE. The "ESD safe" is just a feature which isn't delivered as promised. Since there's a PE terminal the OP should simply crimp a ring terminal to a proper wire, add it it to the PE terminal and solder the other end to the PCB. For $30 I would expect such minor issues.

It may still be ESD safe - the plastics may be static dissipative. I have an Antex iron which is made entirely of partially conductive plastic!

A soldering iron with the tip directly connected to mains earth is IMO not ideal for ESD protection, the idea is any static is SLOWLY discharged. Rapid discharge is exactly what damages components.

[DimitriP]

Long version:  https://www.esda.org/assets/Uploads/documents/OpenForumHandtoolsPrass08.pdf

Short version for the mis-informed, pdf  and  attention-span challenged :

[GEuser]

Ha Ha Ha one could be typing about me too as i'm like that , thanks for putting up the info DimitriP.

With a mains earth tip or a tip at mains earth the only real drama (assuming no other troubles or faults) is Lightning or something like that imo or a storm with real blowy gusting winds , i sure would not be Soldering if i could hear distant Thunder that's for sure .

[madires]

A soldering iron with the tip directly connected to mains earth is IMO not ideal for ESD protection, the idea is any static is SLOWLY discharged. Rapid discharge is exactly what damages components.

When you're concerned about ESD you would have an ESD mat and an ESD wrist strap also. Before soldering anything you would take it with your hands and place it on the mat. That should be sufficient for slow discharging. IIRC, all professional soldering stations got a direct grounding for the soldering tip. There is/was also a US MIL standard about a maximum resistance of 5 Ohms or so.

[Gyro]

I think the CE mark covers electrical safety and not ESD. From a safety point of view the transformer is earthed and double insulated. Maybe connect a 1M ohm from the ground pin on the irons socket to earth, that will give some ESD protection.

Yup, it's a class II device. So, from a safety standpoint of view it would comply with CE. The "ESD safe" is just a feature which isn't delivered as promised. Since there's a PE terminal the OP should simply crimp a ring terminal to a proper wire, add it it to the PE terminal and solder the other end to the PCB. For $30 I would expect such minor issues.

If it's going for class II then those over-long red single insulated mains wires (by the mains switch) really ought to be restrained, so that it's not possible for them to come into contact with anything on the secondary side. A cable tie would take care of that.

Edit: A small point, but important when it comes to certification.

[madires]

Good point! So we can improve that soldering station with just:
- a crimp ring terminal
- a short piece of PE wire
- a cable tie

EUR 0.15 maybe? Don't tell the Chinese manufacturer. He might request US$ 3 more for the improved soldering station 

[KL27x]

delete

[SteveyG]

IIRC, all professional soldering stations got a direct grounding for the soldering tip. There is/was also a US MIL standard about a maximum resistance of 5 Ohms or so.

Most Ersa and Wellers have a 4mm banana plug so you can connect as you please.

[madires]

Most Ersa and Wellers have a 4mm banana plug so you can connect as you please.

The built-in banana plug is connected to PE via a 220 kOhms resistor in my i-Con.

[CapnBry]

Interestingly enough I came here looking for information on a very similar question. I built one of those "T12 digital soldering iron" kits you can get from China. If the earth connection is connected to the iron, the temperature readout bounces all over the place (+/- 50C) such that the controller can't do its job. The connection it has is:
1uF SMD capacitor in the T12 handle  -> Earth Wire to unit -> Controller PCB -> (Earth Connection Point, I have connected to the 3rd plug pin) -> 1M ohm resistor -> DC GND.

Removing the 1uF capacitor disconnects the iron making it un-ESD Safe, but if I do that I measure a 50V square wave with the duty cycle equal to the PWM output of the controller at the tip when referenced to mains earth (on my bench power supply). I've also tried connecting the bench supply's earth connection right to the iron body and this has the same bounce-around effect. This seems like a disaster waiting to happen, right? Soldering on an ESD mat could theoretically push 50V into what I am soldering?

Finally I just tried removing the 1M ohm resistor to DC GND and putting back in the 1uF cap and got the same results. This DIY Kit isn't a triac, it's a DC 24V 3A power supply with a P-Channel MOSFET (I believe) PWMing the soldering iron, so it may be a bit different than your solution.