Hello boys and girls. - Page 1
Forum section: electronics / beginners

author: The March Hare
author_rank: Contributor
timestamp: November 20, 2018, 03:50:44 pm
content: I've heard a rumour that many of my old mates from a place now defunct where the wallpaper was green had migrated here.For anyone requiring a nudge .. IwasJimTheCopierWrench.A bit scary joining a community as a newb - going from electro-god. And so the majority of you still unaware of my predilection of asking "stupid" questions, though not necessarily entirely stupid I'd like to think, as by definition, any scientifically thought provoking question isn't stupid.Either way, thanks for having me.The first Stooopid question posed, to wit:My proto-"shop", such that it is - is situated in the back of an (isolated from earth) van, in a farmer's field, fed with a 150 foot 14/3 extension missing a ground pin. (Hey man, do your science where you can!)As I unbox the contents of my former lab, I'm worried about ESD and my collection of beloved 70's date coded components. It's minus 24 here with nothing for RH.Where to stake a bench to ground reference claim?I'm thinking literally stake a rod into the earth, bond it to the truck chassis, and tie it to neutral. Then of course tap myself out to "earth" before I much about.Thoughts?

author: Ice-Tea
author_rank: Super Contributor
timestamp: November 20, 2018, 04:02:53 pm
content: Welcome JimSo, that place finally kicked the bucket, eh?Putting a stake in the ground is what they did "in the olden days" anyways, so I'd say that should work?

author: The March Hare
author_rank: Contributor
timestamp: November 20, 2018, 07:29:10 pm
content: Aye, she's finally gone s'far as I can tell. Though I hadn't been there much the last while, after being there 30's to 50's there's a definite loss felt.But hey! Ah matey .. one of many friendly old faces, your reply and very presence the nerdly akin to an ex girlfriend calling a bloke up for a roll under the radar; may your iron be hot and your solder still contain leadI'm squarely back in the game.How many of "us" are here??Still having an issue with the algebraic reference though.If I were to be rocking an old regen or crystal set, then an earth stake on the bottom side of the antenna coil would be .. well, in the schematic.Neutral is bonded to the panel at the mast, though code says never the twain shall meet on a branch.If I were to simply bond the truck chassis and (say) the bench surface to hard mother earth, why will my mid 70's NMOS be more grateful than at whatever arbitrary potential they're sitting at presently?

author: Nusa
author_rank: Super Contributor
timestamp: November 20, 2018, 07:36:59 pm
content: Or you could replace the plug on the extension cord with one that HAS a ground pin.

author: Ian.M
author_rank: Super Contributor
timestamp: November 20, 2018, 07:49:02 pm
content: Mains power to your van should go through a GFCI, then local GROUND should be wired to the vehicle chassis, which should also be grounded to a ground stake. You also need an indicator that shows if LINE and NEUTRAL are reversed. If you rarely change locations, a plug-in socket tester might be sufficient. Absolutely do *NOT* bond NEUTRAL to GROUND at your vehicle - that's only permitted by code at the first distribution panel downstream of the utility company's incoming supply.From the ESD point of view, the vehicle body forms an equipotential zone, and that's your local ground reference, so as long as your antistatic gear is grounded to chassis, it no worse than in a fixed workshop. The problem is, if the vehicle body isn't actually grounded, then its possible for enough voltage to build up on the body from atmospheric static to punch through the insulation between the primary and secondary sides of PSUs of any devices that are plugged in - even if they are switched off, and that risks the vehicle body becoming live, and your electrocution stepping into or out of it.

author: The March Hare
author_rank: Contributor
timestamp: November 20, 2018, 08:01:05 pm
content: "Or you could replace the plug on the extension cord with one that HAS a ground pin."Now what kind of science is that??? Geez.Will be eventually rectified to be certain, but I'll still be on 200 feet of extension cord until the spring. Presumably the long run resistance of the panel ground a non issue - at worse tens of Ohms compared to the tens of kilohms of a wrist strap. Still, it's easy to visualize a low impedance circuit - arguably the lower the better. Less clear is unboxing stuff that you've humped across the field mid winter onto a bench with no apparent reference to the universe, never mind the alfalfa.

author: Ian.M
author_rank: Super Contributor
timestamp: November 20, 2018, 08:10:59 pm
content: Light a big bonfire just far enough from the vehicle to be safe to thaw out the ground enough to pound in a ground rod, wire it to chassis and ground of your van's mains panel, then you are no worse off than a fixed lab off a subpanel in an outbuilding.As to unboxing stuff, *IF* the van's well insulated and heated 24/7, a humidifier would help reduce the ESD risk , if you are patient enough to let all packages thermally equilibrate before opening. If the van's not well insulated, or properly heated, a humidifier is just asking for trouble with iceing on the inside of boddy panels, windows etc.

author: The March Hare
author_rank: Contributor
timestamp: November 20, 2018, 08:21:20 pm
content: "Absolutely do *NOT* bond NEUTRAL to GROUND at your vehicle - that's only permitted by code.."Where the hey are the quote tags here?Got what you said. That said, I'm 15 miles from my nearest neighbor, never mind the man - and tend to subscribe to what works so long as it's not likely to kill me.More importantly, just not kaking my retro kit stuff.This particular installation will be "permanent" until I build a real shop. Daddy needs to do electronics even if it's 16 below.Need to look up the term "equipotential" .. My worries snuffling my fat arse through a few hundred feet of snow in rubber boots, entering an isolated from earth box, and suddenly acquiring the touch of silicon death.

author: The March Hare
author_rank: Contributor
timestamp: November 20, 2018, 08:26:45 pm
content: There is no van main panel. just a place, soldering station and light, to keep me happy until I build a real shop. Absolutely ghetto. A 14/3 extension cord powering the works. I haven't soldered anything in a year and I'm losing my mind.

author: Ian.M
author_rank: Super Contributor
timestamp: November 20, 2018, 08:38:05 pm
content: At the very least, you need a circuit breaker and a GFCI between the van end of the extension lead and any mains powered stuff in your van, and as I explained earlier, grounding the vehicle chassis is advisable. If you don't bond the chassis to ground of the mains sockets, the odds are you'll kill everything sensitive you touch with a soldering iron bit.

author: The March Hare
author_rank: Contributor
timestamp: November 20, 2018, 08:54:25 pm
content: Got it. Local earth stake to body bonded to ground terminal of feed from panel to field. GFI is for school girls.Later: (lol), the issues of carbon steel stake, copper wire, and aluminum van body. Isn't engineering awesome?

author: Ian.M
author_rank: Super Contributor
timestamp: November 20, 2018, 09:13:00 pm
content: No, a GFCI is essential because you don't know what the resistance of the ground stake will be, in possibly frozen ground. If it too high a fault to ground may not trip the breaker, then you could die entering or leaving the vehicle.Don't worry about electrolytic corrosion as long as you dont let the snow build up against the wheels or under the chassis, and you've used Noalox or dialectric grease to keep moisture out of connections between dissimilar metals. The ground stake to ground wire connection should be sealed with self-amalgamating tape, then put a pop can over it to keep the weather out.OTOH if you cant prevent snowdrifts building up to the vehicle body, you are in for a world of grief and should probably get an isolating transformer so you can tie Neutral to chassis on its secondary side to prevent stray currents from mains equipment eating holes in the bodywork.

author: Brumby
author_rank: Unknown
timestamp: November 21, 2018, 01:21:48 am
content: Firstly - Welcome!Secondly:Quote from: The March Hare on November 20, 2018, 08:21:20 pm

author: Ice-Tea
author_rank: Super Contributor
timestamp: November 21, 2018, 11:33:11 am
content: Quote from: The March Hare on November 20, 2018, 07:29:10 pmTim's here. Other than him.. Uh.. Treez? Remember him? Look up his nick and be prepared for a few hours of top notch entertainment

author: The March Hare
author_rank: Contributor
timestamp: November 21, 2018, 01:27:29 pm
content: Quote(Thanks for the quote hand hold)Good point. The relatively skinny and long run out with (3 total) interconnects might not even pop a 15A breaker hot to neutral short.I have a "scrap network" that I've put it out to that I'm looking for 200 feet of 8/3 (so I can run my hobby Lincoln in my bus project next year), but with much on the go and the back of the van an interim "mistress bench" there's not ten dollars to invest.Still, might as well do it more or less right. Though this might be a first.Frost hasn't set in yet though the days are short .. today going to mig a fireplace poker to a bit of discarded bus crossmember and get it down in the muskeg before work.

author: Ian.M
author_rank: Super Contributor
timestamp: November 21, 2018, 02:56:34 pm
content: Great. It is possible to bodge it safely for no more than the cost of a GFCI (+ whatever the ground stake ends up costing).On the subject of electrolytic corrosion - the best bet is going to be to prevent snow buildup under the van in the first place. Rigging up a skirt round the body made of cheap poly-tarp with the bottom edge dug in or heavily sandbagged is probably the best option, and it will make the van a lot warmer if you have mostly still air under the floor. Take care you don't block any vents, and maybe leave a small gap by the fuel tank filler and to under the engine so fumes dont build up. Dig out any drifts till the skirt is at least 50% exposed and wind flexing it will keep it clear of possibly conductive iceing.

author: The March Hare
author_rank: Contributor
timestamp: November 23, 2018, 05:11:31 am
content: Lol, had forgotten until this morning that it had slipped my mind .. I parked the rig on an outcropping of exposed granite so she wouldn't sink into the thawing muskeg in the spring.Best try today was only four inches of stake (galvanized steel angle) penetration until shield, and conspicuously loose in the ground.Understand this is not by any means a permanent, or even overly useful setup.I've just been out of things for awhile and I'm dying to solder something .. anything. Even though it's minus 20 today.The bench "mistress" requirements (until my awesome real shop is completed next summer) is a soldering station and light. No heat, no scope or plug in test gear. Ah, and probably a wall wart powering whatever I'm working on.A hot to body fault is less likely than me slipping on the van step and breaking a hip. My concern is ESD toasting antique kit.Don't take this as moron too dense to understand your advice.Put a new end on the cord today with a ground lug. so the 4 outlet strip on the plywood bench has "some" panel earth reference at the bench. the interconnects between cords I've strung through a concrete block on end covered with a plastic pail .. ghetto as can be. Gave the male ends a quick scotchbrite. Probably useful for 600 at best of the 1875W available at the outlet.I doubt I'll ever draw 150.Chinese GFI's are cheap here .. so I'll pop one in next week - as well as better ends on the cord and a permanent weatherproof bond between cords (Though the bigger issue at the moment is no proper feed through the wall and squishing the cord under the door), but consider the setup akin to not much more than running a soldering iron on a few hundred feet of extension rather than a laboratory setup.

author: Ian.M
author_rank: Super Contributor
timestamp: November 23, 2018, 05:44:30 am
content: If you've got a ground in the long extension cord, a GFCI to save your ass when the ground resistance is too high for a fault to ground to trip the breaker, and you bond the van body/chassis to ground you should be fine both for electrical safety and on the ESD side of things, except for the possibly very low humidity once winter really gets going, which means you'll need to be extremely careful to take full ESD precautions when handling stuff that's even *slightly* ESD sensitive.It still wouldn't be a bad thing to have a local ground stake. Maybe you can find a spot at the edge of the outcrop, or a pocket where there's more soil?Its going to be pretty miserable in the van without heat, so unless it has a properly installed diesel heater (and you can run a battery charger to keep up with its 12V load), you'll probably need to run a mains heater.

author: spec
author_rank: Frequent Contributor
timestamp: November 23, 2018, 07:28:45 am
content: Quote from: The March Hare on November 20, 2018, 03:50:44 pmWelcome TMHWhat is this place

author: Ice-Tea
author_rank: Super Contributor
timestamp: November 23, 2018, 09:07:33 am
content: A once popular electronics forum, Dutchforce.

author: The March Hare
author_rank: Contributor
timestamp: November 23, 2018, 12:25:00 pm
content: QuoteAyuh .. She certainly shone brightly in her day..QuoteDropped 13 since midnight, when I tried to unwrap a cord and it snapped. Just woke up to minus 31 according to the wireless.Even better than a van, if you're visualizing an E-350 - an uninsulated and poorly sealed aluminium body.You can clearly see how much I miss a bench.I'll need a proper (heavy) panel service to my (big) bus eventually when I start putting the floor back in, but 250 feet of 8/3 isn't in the budget right now.Wife has a naptha camp stove somewhere.. and don't they say CO is great for that warm fuzzy feeling?

author: Ian.M
author_rank: Super Contributor
timestamp: November 23, 2018, 01:02:55 pm
content: Don't go the camp stove route - any reasonably compact combustion heater except a room-sealed balanced flue heater will either kill you with CO, or at least make you as sick as a dog and stupid to boot, before it warms up the van enough to work comfortably. A small stove just cant put out enough heat to make up for the heat loss via the ventilation it needs to burn safely.Can you get hold of enough straw bales to stack round it up to roof height, some insulation boards to go across the top, and some big heavy tarps to keep the weather out of the bales and hold the insulation boards down etc. to provide enough insulation that you can survive in the van with the limited wattage electrical heat you can run?Otherwise you'd need to get and fit a 12V diesel fuelled truck heater, and a RV/marine permanently installed battery charger to 'float' the battery while keeping up with the diesel heater's electrical load. Take care the heater's balanced flue/vent is somewhat sheltered from direct high winds or the heater will probably keep on blowing out and going into emergency shutdown when you need it the most.