They were initially quoted 12,000 dollars to put one in. If that wasn't high enough now they are wanting $120,000. It is guarenteed but why on earth is it so high? I know another place near here had alot of trouble with the ground they installed for their plams cutting table. they ended up putting 75 rods in and still were burning up boards but why is this so hard? It is very rocky here (Ozarks) and they probably ;have to blast but still. Ken
That's nuts.
That's really insane. A ground is a resistive connection to the earth - preferably a low resistance. What you need to do is bond every metal item in the shop to every other one and make as good a connection as you can to what ground there is. There's no point drilling in rock - won't help. I'd be inclined to consider burying a metal net in whatever soil there is. What does the local inspector say?
Been there, done that. In rocky soil, too. If buried rods don't work, consider using a large copper plate and put Calcium Chloride under it and on top of it before burying it. Lay it flat. Two of three feet underground should be sufficient.
That worked for me.
snipped-for-privacy@yahoo.com wrote:
Local inspector? No such thing. This is Arkansas I did find out that its solid rock 2 feet down. This ground has to be
3 ohms or less I believe. i don't see what good "bonding to every metal item in the shop" would do. This seems like it would just complicate everything. They were talking about drilling a well or finding a well that supposedly was on property years ago. Ken
what if its solid rock down two feet? Should they build up the soil? They are talking of drill a well. Ken
You have a problem. It is not caused by a voltage difference to ground per se. If the entire shop was 2000 volts above ground it should still work (though I wouldn't want to be near it). If you have, for example, a reinforced cement floor, the steel in that should be bonded to the plasma cutter as should everything else.
Grounding makes all 'ground' voltages equal and bonding does the same. Your local library will have a code book and electrical books which will explain things more fully but the key is bonding. Example: when I installed my brother's washing machine I cut off the plug and wired it directly into the wall - that way the ground wire cannot be disconnected short of cutting the wire.
Our local library didn't have it. In these small towns they seem to put all their money into hiring relations to stand around and not buying books. I will get it though and look into all you mentioned. thanks for the help Ken
Maybe you can get
There's some basic info here
Google for (electrical code grounding)
"It has been determined that over 70 per cent of all electrical problems in industrial, commercial and institutional power systems are due to poor grounding and wiring errors. Without proper grounding, sensitive electronic equipment is subjected to destruction of data, erratic equipment operation, and catastrophic damage. "
I'm going to try the interlibrary route and looked thru the links and will start doing my homework. I've learned already my assumptions about grounding wire were wrong. Thanks Ken
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