Maker Pro
Maker Pro

Need Earth Ground Without Drilling a Hole

D

D from BC

Jan 1, 1970
0
Let's say this is the screw ( ==<| )
It's the < that's 100deg...if I understand..
I'll look around for those..

I don't know much about welding 4mm threaded studs on aluminum
sheeting but I like the idea because no drilling, grinding, hammering
or clipping..
I also can dodge finding special rivets, tools, anvils and fasteners.

But..I'm not getting a welder just to weld studs 10 times/year... :(


D from BC
 
R

Rich Grise

Jan 1, 1970
0
Now, should one use an internal or external shakeproof washer here ?

AFAIK, it's an aesthetic choice, i.e., do you want the teeth to show or
not?

Cheers!
Rich
 
R

Rich Grise

Jan 1, 1970
0
D

D from BC

Jan 1, 1970
0
He's talking about external-tooth vs. internal-tooth lockwashers - they
even have them with both external/internal teeth!

http://www.mcmaster.com/nav/enter.asp?pagenum=3142
http://www.mcmaster.com/nav/enter.asp?pagenum=3143

And, obviously, it goes on the inside of the box.

Cheers!
Rich

Ohhhh.. :)
Thanks
This looks good..
Lots of teeth to bite into the metal for 15amp current.
And compression to prevent looseness.

My app is exposed to vibration from passing traffic..

Maybe Loctite threadlocker could be a way of dodging washers?
D from BC
 
J

John Fields

Jan 1, 1970
0
Ohhhh.. :)
Thanks
This looks good..
Lots of teeth to bite into the metal for 15amp current.
And compression to prevent looseness.

My app is exposed to vibration from passing traffic..

Maybe Loctite threadlocker could be a way of dodging washers?
D from BC

---
You could use Loctite, but the washer is there to bite into the
aluminum so you'll get good electrical contact through the oxide.

If you use PEM threaded studs all that electrical stuff happens
automatically when the stud is pressed in and then it's your choice
whether you use an anaerobic adhesive and/or lock washers for the
mechanicals.
 
R

Rich Grise

Jan 1, 1970
0
Ohhhh.. :)
Thanks
This looks good..
Lots of teeth to bite into the metal for 15amp current. And compression to
prevent looseness.

My app is exposed to vibration from passing traffic..

Maybe Loctite threadlocker could be a way of dodging washers? D from BC

That won't give you a reliable connection - you need to dig through the
oxide and form a gas-tight metal-to-metal contact.

But Loctite is not a bad idea either - just keep the washer for the
electrical continuity.

Good Luck!
Rich
 
M

Mark Zenier

Jan 1, 1970
0
How is a PEM fastener going to work if you can't drill a hole?
Either I'm missing something here, or....

PEM has studs which are spot welded on. (I think it was PEM, but it was
also 25 years ago). But you'd need to find a sheet metal shop that had
the custom welder for a one-off.

Mark Zenier [email protected]
Googleproofaddress(account:mzenier provider:eskimo domain:com)
 
J

John Fields

Jan 1, 1970
0
Let's say this is the screw ( ==<| )
It's the < that's 100deg...if I understand..
I'll look around for those..

I don't know much about welding 4mm threaded studs on aluminum
sheeting but I like the idea because no drilling, grinding, hammering
or clipping..
I also can dodge finding special rivets, tools, anvils and fasteners.

But..I'm not getting a welder just to weld studs 10 times/year... :(

---
Here's a find:

http://www.smithfast.com/msflathead.html

Now you can figure out whether a 100° screw will fit properly!
 
J

Jamie

Jan 1, 1970
0
D said:
I didn't express the problem accurately...
Better expressed:
I need to bond a ground wire inside a box but I don't want to create
any external protrusions.
There are PEM's that can be countersunk and have thin heads.

Someday I'd like to weld an aluminum bolt to the inside of the box for
an earth ground connection.
Anybody here do little welds like that?

D from
I'm only guessing, is this like a pot metal box?, if so, how about a
partial hole drilled and use a bottom tap to put in a bonding lug?
 
J

Jasen

Jan 1, 1970
0
A 15Amp draw trips the circuit breaker in the electrical room.

after about a minute it does.

if the live shorts to the box hundereds of amps will flow.

the earth connection has to keep the box at a safe voltage until the
breaker opens.

Bye.
Jasen
 
D

D from BC

Jan 1, 1970
0
after about a minute it does.

if the live shorts to the box hundereds of amps will flow.

the earth connection has to keep the box at a safe voltage until the
breaker opens.

Bye.
Jasen


Yeah.... that breaker needs some heating time... It's a thermal
mechanical device. Meanwhile current runs high.
I thought shooting for a 15amp continuous fault current earth ground
connection might get me in the ball park.
Hopefully the breaker trips before the earth ground connection burns
open due to contact resistance..
D from BC
 
R

Ross Herbert

Jan 1, 1970
0
agencies ?

It's indirectly because of the resistance - at a certain current level,
the I^2R will heat up the solder, which _could_ melt and leave
you with an open ground, which depending on the fault, could make
the equipment dangerous to touch.

Cheers!
Rich


It is also easier to visually determine the quality of the ground
connection where a mechanical type solid connection eg. stud/screw,
shakeproof washer and nut, is used. A soldered joint is harder to
perform properly and the quality of connection is not easily
determined by visual inspection. For safety ground connections in
particular, I think you will find that a mechanical connection is
specified as the standard by most safety authorities.

I have seen quick connect (QC) tabs and push-on terminals used for the
safety ground connection on domestic appliances such as fridges, but I
am not sure if they are acceptable unless the cable end connector is a
locking type which cannot dislodge due to vibration or other accident.
 
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