Lathe electrically "hot" due to VFD? WTF?

Further to this discussion, and not in response to any particular post, Plumbers are not great fans of cold water pipes being used as electrical grounds. And for good reason. If there is a ground fault, and the pipe is carrying any current, and a plumber has to cut the pipe to do a plumbing repair, that current tries to pass through the plumber.

Also, any plastic pipe in the system obviously has to be bypassed with wire, though it ususlly isn't, resulting in bad (no) grounds downstream of the plastic.

IMO, if you are going to use the cold water pipe as your ground connection, you really ought to do it right at the point where it enters the building, before any plumbing connections (which could corrode and develop high resistance.

I'm getting ready to replace my service entrance, and there will be multiple ground rods.

I found one when I helped a friend move into a rented house. The panel was at the front of the house and had a 3#8 stove cable going into the wall. The kitchen at the back of the house had an identical 3#8 cable coming out of the wall to connect to the stove. When I hooked up the stove and re-inserted the fuse carrier, one of the fuses popped. The replacement fuse cured the problem but we soon noticed an odd smell. Turns out, the replacement fuse was higher rated and further investigation revealed that when the kitchen had been moved to the back of the house, the stove cable had been extended with 3#14 cable and cross wired so that line 1 was connected to the neutral. There was enough current to blow the 40 A fuse but not the 60A which heated the #14 wire running through the attic Gerry :-)} London, Canada

When I re-wired my previous house, I moved the service panel to directly below the kitchen. Since I had a good supply of salvaged, bare, #6 stranded wire, I ran that from the incoming water line through the service ground lug the and further on to connect both hot and cold feeds and the copper drain at the kitchen sink. The inspector thought that the drain line grounding was such a good idea, I gave him an extra ground clamp and enough wire to modify his own home system.

He told me the story of the guy that wired his rec. room much more cheaply than anyone else. Investigation revealed that all his wire was

300 ohm twin lead. Gerry :-)} London, Canada

Here in the UK that's compulsory, known as "supplemental bonding" of basically all metalwork that could be touched in "special locations", i.e. kitchens, bathrooms... Some "electricians" go to town and have ugly cables appearing from floors to bond the central heating radiators and handrails too, rather than make an effort and lift a floorboard :( We're not allowed to use the water supply pipe as a protective earth (ground) though, as a lot of homes now have plastic incoming pipework!

Is electrical work as tightly regulated in the US as it is here? We've had new laws ("statutory instruments" that don't go before a vote in Parliament) inflicted on us that pretty much outlaw DIY electrical work beyond replacing an existing switch, light fitting, socket or piece of damaged cable etc. (and not even that in the bathroom and kitchen!), the local council building control office have to be informed and handed inspection certificates (produced by members of an "approved scheme" who often refuse to certify anyone else's work or charge almost as much as having them do the work from start to finish) etc. - of course, this has resulted in "old colours" cables selling at a premium as the new laws came in after a change of cable core colours and another result is that more and more people are tripping over overloaded extension cables... The law (Part P of the Building Regulations) was put in force after a politician's son-in-law screwed a metal shelf in through a cable in the wall without checking for cables first, and his wife died from touching that and her dishwasher, so it got blamed on the contractor - no avoiding stupidity I guess, however hard Nanny tries to legislate, the only law you can really count on is Darwin's...

Friends of mine bought a falling-down farmhouse in La Belle France a few years ago, and discovered the wiring was mostly bell-wire (that you'd use to connect a doorbell button) - nice when they plugged in a 3KW heater and wondered what the burning smell was! A rewire was one of the first steps in the rebuild, and done to the same standard they've applied to the rest of the building - damn near perfect :)

Dave H.

You have quite insane gun control too, now people cannot own guns and cannot install receptacles, pretty weird country I would say.

i

You might feel it's an unneccessary issue, Ig... so you apparently believe you should have that freedom (assuming that you believe you're intelligent enough to do work like this),

..and yet, your lathe has probably had a ground fault for all this time.

An earth ground is a single conductor.. how hard can it be?

When wiring anything that's line powered.. a replacement receptacle or a major piece of equipment, the first connection I make is to a known good earth ground. The earth ground doesn't get disconnected until the equipment is taken out of service, with all power conductors removed (bare ends cut off or capped with wire nuts).

Everyone doing any electrical work should know how little electrical current it takes to disrupt normal heart rhythm. This info is included in NEC manuals and numerous other sources.

ote:

Most ridiculous.

i

Agreed, safety is important, I've gone a bit over the top for my shed/workshop, 100mA time-delayed RCD ( = Residual Current Device, see below) on the armoured cable from the house, another (30mA instantaneous) for everything but the lights so I won't be left in the dark with spinning machines, separate circuit breakers for each machine and the local outlets, but a lot of people will be using 25 yards or more of trailing extension cable across the garden and through puddles if they want to use anything electrical beyond the confines of the house: this is perfectly legal but bloody dangerous, rather than having a properly-wired fixed installation which would be very much safer but which they currently aren't permitted to install - anyone with an ounce of sense will find out how to do it properly (there are plenty of resources online), anyone without... well, maybe they should be shooed out of the gene pool before they drown someone else ;)

As for Iggy's ground fault - could be an existing fault and nothing to do with him and his electrical work, lucky he found it now and not when a

*major* fault occured! I've seen quite a few horrors installed by "approved electricians" and some really excellent jobs by DIYers - one that comes to mind was aluminium cables terminated to brass connectors, first sign of damp and they start to corrode, resistance goes up and it overheats, up in smoke goes the junction box, possibly followed by the house... That was a "professional" installation too :(

I have an electrical + electronic engineering cert. that took 3 years post-college and several years practical experience on everything from 20KV transmitter supplies to 100HP servomotor systems but according to the regulations here I'm not a "competent person" to work on electrics in my own home, unlike a guy straight out of school (where he failed all his courses) who's done a one-week course on testing *and has paid a huge amount for membership* in one of the "approved bodies" who run the certification scheme and lobbied (mostly in the newspapers) for the change in the law. Makes you think, eh?

Part of the current regulations here that I approve of is whole-installation

30mA RCD protection, so the power will disconnect in a few milliseconds if there's any more than a 30mA current difference between phase and neutral - but even that won't save those who put themselves between phase and neutral without earthing themselves! Against stupidity the gods themselves contend in vain...

Dave H.

Proof that it's not just our gov't which has gotten _completely_ out of control. Guns, electricity, knives, and now extinguishers? Man...

-- Ask not what the world needs. Ask what makes you come alive... then go do it. Because what the world needs is people who have come alive. -- Howard Thurman

In most places in the US, local laws set the specific requirements and usually compliance with the National Electrical Code is one of them.

My first home was in a city that forbid anyone but a non-licensed electrician from doing andy electrical work. Where I live now, a homeowner can do any electrical work providing he can submit a building permit request, get it approved, and pass an inspection by the city building inspector.

I installed a 50 ampere subpanel along with lights and 220 outlets for lathe, mill and welder and had no problem with either the permit or the inspection.

About 25 years ago I designed several test fixtures for the computer company I worked for and sent two of them to our plant in Woking/Bracknell. I visited the plant a few months later and was surprised at the extensive plexi/perspex covers they installed over it.

Can the Brits on the group confirm that the UK is really outlawing fire extinguishers?

Joe Gwinn

The fact that Iggy had a ground fault does not mean Iggy is not competent. The ground fault may have been in wiring which had been done before Iggy bought his house.

But Iggy may now see the wisdom of not trusting others to do competent work. The house I now own was built about twenty years before I bought it.. After I bought the place, I checked every outlet to see if it was correctly wired. I found about five outlets that were not correctly wired. I suspect the incorrect wiring was done when the place was built. Why the errors were not found during the original inspection is a mystery.

Most of the places I have lived, allow the owner to do wiring and plumbing to his own residence. This has more to do with how much political power the unions have than anything. Wiring is not rocket science.

Dan

The ACPO (Association of Chief Police Officers) would like private individuals to be banned from having machine tools, too - apparently we "could make guns with them"...

I'd have thought you could make a Sten with hand tools, that's why they called 'em the "plumber's gun"!

Dave H.

Is that a joke?

Ban police officers. They kill more than 21x more people than machine tool users make guns. (cop suicide rate 22 per 100,000)

-- Ask not what the world needs. Ask what makes you come alive... then go do it. Because what the world needs is people who have come alive. -- Howard Thurman

Like you stated, wiring isn't rocket science, but then many other things aren't rocket science either.

The part about "known good earth ground" got snipped.

***When wiring anything that's line powered.. a replacement receptacle or a major piece of equipment, the first connection I make is to a known good earth ground.***

He may or may not be an intelligent electrician, but he's had his children and wife living in that house. So who is responsible for confirming that the electrical system is safe? Realtor, gubmint, seller, inspector, non-existent contractor etc.

The thing is, none of those other people sleep in that house, and they'll all just point their fingers at each other, eventually assigning blame to who ever makes the best scapegoat. The other people's responsibility most likely ended with the sale of the house.. and that leaves only one other person.

The responsibility ends up being the homeowner's.

I think the majority of home fires are determined to have been caused by "faulty wiring". There hasn't been a lot of wire being sold that doesn't meet specifications. Realistically, many home fires are caused by improper installations or misused circuits and/or misused electrical equipment.

A person can buy or find free information WRT safe, proper wiring practices, so there aren't many reasons why wiring should be done improperly, but one reason is arrogance (which is essentially choosing to be ignorant).

I've seen a lot of horrible electrical work.. including a spliced & taped romex junction (no wire nuts with a branch meeting a run, adding 12 to 14ga) hanging free inside a wall without a box.

People are stupid, but add tighter-than-a-frog's-ass cheap to stupid, and they'll perform feats that are difficult to imagine, by anyone with the slightest amount of common sense (which needs to be renamed uncommon sense, as it seems to be fairly scarce nowadays).

Don't some still use the old wooden water supply pipes?

Union influence? - I refused to even consider going on a holiday to help senior son renovate his 100+ year old house in Walthamstow ~2002

Gerry :-)} London, Canada

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