How to attach large house wiring to PCB?

[Michael]

Hi - I'm finishing drawing a board that will be switching some house
wiring, which will be carrying about 5 amps. Can I just solder the wires
directly to the board? Is there any problem with doing that? I don't see
why not - but I'm just not used to dealing with so much power. Thanks!

Michael

 

[Ken Taylor]

Hi - I'm finishing drawing a board that will be switching some house
wiring, which will be carrying about 5 amps. Can I just solder the wires
directly to the board? Is there any problem with doing that? I don't see
why not - but I'm just not used to dealing with so much power. Thanks!

Michael

Um, is this 110/240VAC?

Ken

 

[Walter Harley]

Hi - I'm finishing drawing a board that will be switching some house
wiring, which will be carrying about 5 amps. Can I just solder the wires
directly to the board? Is there any problem with doing that? I don't see
why not - but I'm just not used to dealing with so much power. Thanks!

It depends on whether you're planning on having your house burn down
sometime soon. If your insurer or landlord or fire marshal or whomever
finds out you've got a non-code, non-UL-listed device permanently installed,
good luck making a claim. Other than that issue, and the fact that
soldering 12 gauge stranded wire to a PCB isn't exactly easy, and the fact
that vibrations and strain on the wiring will soon rip the traces off the
PCB, you'll be fine. But you'd be a lot finer if you used some sort of
Euroblock type connector, rather than soldering directly to the PCB. Plus
that way you can take it apart again when it doesn't work.

A better solution would be to have your device do everything *but* switch
the mains. Leave the switching to an approved relay in an approved box;
have your device control the relay.

Mine is the opinion of someone who is not a licensed electrician, nor a
lawyer, nor a safety expert. (But I have spent a chunk of time perusing the
US electrical code. And done a bunch of mains wiring.)

 

[Michael]

It depends on whether you're planning on having your house burn down
sometime soon. If your insurer or landlord or fire marshal or
whomever finds out you've got a non-code, non-UL-listed device
permanently installed, good luck making a claim. Other than that
issue, and the fact that soldering 12 gauge stranded wire to a PCB
isn't exactly easy, and the fact that vibrations and strain on the
wiring will soon rip the traces off the PCB, you'll be fine. But
you'd be a lot finer if you used some sort of Euroblock type
connector, rather than soldering directly to the PCB. Plus that way
you can take it apart again when it doesn't work.

A better solution would be to have your device do everything *but*
switch the mains. Leave the switching to an approved relay in an
approved box; have your device control the relay.

Mine is the opinion of someone who is not a licensed electrician, nor
a lawyer, nor a safety expert. (But I have spent a chunk of time
perusing the US electrical code. And done a bunch of mains wiring.)

About how much do such relays cost?

 

[Michael]

Um, is this 110/240VAC?

Ken

yes - 110VAC

 

[Michael]

It depends on whether you're planning on having your house burn down
sometime soon. If your insurer or landlord or fire marshal or
whomever finds out you've got a non-code, non-UL-listed device
permanently installed, good luck making a claim. Other than that
issue, and the fact that soldering 12 gauge stranded wire to a PCB
isn't exactly easy, and the fact that vibrations and strain on the
wiring will soon rip the traces off the PCB, you'll be fine. But
you'd be a lot finer if you used some sort of Euroblock type
connector, rather than soldering directly to the PCB. Plus that way
you can take it apart again when it doesn't work.

A better solution would be to have your device do everything *but*
switch the mains. Leave the switching to an approved relay in an
approved box; have your device control the relay.

Mine is the opinion of someone who is not a licensed electrician, nor
a lawyer, nor a safety expert. (But I have spent a chunk of time
perusing the US electrical code. And done a bunch of mains wiring.)

Do you know anything more about such relays? Like how much they cost, where
they can be found, etc.? I've never seen any.

Michael

 

[Rheilly Phoull]

Do you know anything more about such relays? Like how much they cost, where
they can be found, etc.? I've never seen any.

Michael

Michael
It might be a good idea to do a bit of study on wiring regulations and
general pratice before jumping in. Relays of the sort you mention are used
in millions in industry and any electronics supplier of any worth can sell
you one. For the sort of project you are describing the normal approach is
as mentioned by others, also for service and safety it is the best. Just
make up your control electronics and house them suitably and run the low
voltage contol wiring into a seperate mains enclosure with the relay. That
enclosure should be installed according to the wiring codes that apply to
your area. The two voltage levels (control and mains) should also be
isolated according to the code.
Sure it costs more but when you alter the installation in your home or
whatever, you then are required to conform to the code and should you be
unlucky enough to have a problem your work would come under scrutiny of the
various authorities, also insurance companies are not known for their
compassion in such cases.
Don't let the advice we have given you curb your enthusiasm for an
interesting pursuit but be aware that mains supply installations do require
knowledge and experience.

 

[mike]

Hi - I'm finishing drawing a board that will be switching some house
wiring, which will be carrying about 5 amps. Can I just solder the wires
directly to the board? Is there any problem with doing that? I don't see
why not - but I'm just not used to dealing with so much power. Thanks!

Michael

The consensus seems to be that you're modifying existing house wiring
to do this job. If that's the case, your problems are more legal,
safety, insurance and the fire department than technical. Read up on
the electrical code before emabarking on this project.
What you can do is more dependent on the size of the breaker than the
load you anticipate. Soldering is normally frowned upon.

You'd be much better of to put the whole thing in a metal box with
a power cord that plugs into the wall. That limits your issues.

Never mess with the house wiring unless you're a licensed electrician
or get it approved by one.
mike

--
Return address is VALID.
Bunch of stuff For Sale and Wanted at the link below.
Toshiba & Compaq LiIon Batteries, Test Equipment
Honda CB-125S $800 in PDX
TEK Sampling Sweep Plugin and RM564
Tek 2465 $800, ham radio, 30pS pulser
Tektronix Concept Books, spot welding head...
http://www.geocities.com/SiliconValley/Monitor/4710/

 

[Michael]

The consensus seems to be that you're modifying existing house wiring
to do this job. If that's the case, your problems are more legal,
safety, insurance and the fire department than technical. Read up on
the electrical code before emabarking on this project.
What you can do is more dependent on the size of the breaker than the
load you anticipate. Soldering is normally frowned upon.

You'd be much better of to put the whole thing in a metal box with
a power cord that plugs into the wall. That limits your issues.

Never mess with the house wiring unless you're a licensed electrician
or get it approved by one.
mike

well - I only am making one of these - and it's going in my own home - and
most importantly - only ONE wire will be going through the circuit that I'm
building. Thus - there is no worry of short circuits, fires, or anything -
because the other wire will be in an insulated wire away from the circuit.
So surely none of you can find fault with that? BTW - the circuit
replicates a three way switch by replacing a three way switch with a SPDT
relay.

Michael

 

[mike]

well - I only am making one of these - and it's going in my own home - and
most importantly - only ONE wire will be going through the circuit that I'm
building. Thus - there is no worry of short circuits, fires, or anything -
because the other wire will be in an insulated wire away from the circuit.
So surely none of you can find fault with that?

Your response is classic.
The statements made above are clear
evidence that YOU should NOT be doing this.
mike

BTW - the circuit

replicates a three way switch by replacing a three way switch with a SPDT
relay.

Michael

--
Return address is VALID.
Bunch of stuff For Sale and Wanted at the link below.
Toshiba & Compaq LiIon Batteries, Test Equipment
Honda CB-125S $800 in PDX
TEK Sampling Sweep Plugin and RM564
Tek 2465 $800, ham radio, 30pS pulser
Tektronix Concept Books, spot welding head...
http://www.geocities.com/SiliconValley/Monitor/4710/

 

[Rheilly Phoull]

well - I only am making one of these - and it's going in my own home - and
most importantly - only ONE wire will be going through the circuit that I'm
building. Thus - there is no worry of short circuits, fires, or anything -
because the other wire will be in an insulated wire away from the circuit.
So surely none of you can find fault with that? BTW - the circuit
replicates a three way switch by replacing a three way switch with a SPDT
relay.

Michael

Stay with the plan mate but look at the big picture, you are missing out on
the practical issues !!

 

[Keith R. Williams]

A better solution would be to have your device do everything *but* switch
the mains. Leave the switching to an approved relay in an approved box;
have your device control the relay.

X10

 

[Keith R. Williams]

well - I only am making one of these - and it's going in my own home - and
most importantly - only ONE wire will be going through the circuit that I'm
building. Thus - there is no worry of short circuits, fires, or anything -
because the other wire will be in an insulated wire away from the circuit.
So surely none of you can find fault with that? BTW - the circuit
replicates a three way switch by replacing a three way switch with a SPDT
relay.

I'm with the others. This is a *DUMB* idea. Why not a 3-way X10 unit?
(if you even need to get that fancy). House wiring just isn't
something to fool around with. Too many things can go wrong and the
results aren't good.

 

[Fred Bloggs]

well - I only am making one of these - and it's going in my own home - and
most importantly - only ONE wire will be going through the circuit that I'm
building. Thus - there is no worry of short circuits, fires, or anything -
because the other wire will be in an insulated wire away from the circuit.
So surely none of you can find fault with that? BTW - the circuit
replicates a three way switch by replacing a three way switch with a SPDT
relay.

Michael

Bring the control board input/output wires out so that you *wire-nut*
them into the mains wires- do not solder those connections. If the board
is going in a mains junction box, then it is better to use a *terminal
strip" with screwdown connections for the mains wiring- same method of
attachment as used on receptacles for example.

 

[Ken Smith]

Hi - I'm finishing drawing a board that will be switching some house
wiring, which will be carrying about 5 amps. Can I just solder the wires
directly to the board? Is there any problem with doing that? I don't see
why not - but I'm just not used to dealing with so much power. Thanks!

Read the other answers and also think about the stress you will be
applying to the PCB with the stiffness of the wire.

If this is a product (vs home project) put something like Phonix
connectors on the PCB.

 

[Michael]

Your response is classic.
The statements made above are clear
evidence that YOU should NOT be doing this.
mike

Eh - I'm not following. Why is that NOT safe? Seriously - I am interested
to hear what aspect of this design is unsafe - because I too was hesitant
about working with housing wiring - but then I designed this and thought it
was a great solution.

Michael

 

[Rheilly Phoull]

Read the other answers and also think about the stress you will be
applying to the PCB with the stiffness of the wire.

If this is a product (vs home project) put something like Phonix
connectors on the PCB.

I wonder if this lad is related to the "AC DC Dude" who used to post here ??

 

[Active8]

[/QUOTE]

what if the load outside the box shorts

fires,

and the switching device or pcb trace catches fire?

or anything - because the other wire

which it wouldn't hurt to *also* switch with a relay...

will be in an

and there will be no safety ground to return the current to ground
when the energized wire melts its solder joint and falls on the
inside of the enclosure you're holding in one hand while your other
hand or foot is grounded to whatever. Do the EMTs know which
hospital you prefer or should they just get you to the nearest one?

So surely none of you can find

Not if your real objective is electrocution or fire.
Yeah. Find an electrician preferably one that's familiar with plant
control wiring, not just somone whose pulled residential wiring his
whole career. Get him to leave you a pair of low voltage control
wires or maybe some scew terminals that you can connect to without
having to access the inside of the enclosure. Then the worst you
can do is fry your relay coil.

Eh - I'm not following. Why is that NOT safe? Seriously - I am interested
to hear what aspect of this design is unsafe - because I too was hesitant
about working with housing wiring - but then I designed this and thought it
was a great solution.

A common mistake that people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools.
-Douglas Adams

 

[Michael]

what if the load outside the box shorts[/QUOTE]

It was installed by a professional licensed electrician - and has been
working for nearly 20 years now - so that is not quite a worry.

and the switching device or pcb trace catches fire?

I already asked about proper trace design - so this is not a worry. The
relay I'm using is rated for double the current that it will experience
- so that also isn't a worry.

which it wouldn't hurt to *also* switch with a relay...

Umm, why?

and there will be no safety ground to return the current to ground
when the energized wire melts its solder joint and falls on the
inside of the enclosure you're holding in one hand while your other
hand or foot is grounded to whatever. Do the EMTs know which
hospital you prefer or should they just get you to the nearest one?

I don't even need to respond to this.

Not if your real objective is electrocution or fire.

Right. Those are exactly my objectives.

 

[JeffM]

what if the load outside the box shorts

and the switching device or pcb trace catches fire?

which it wouldn't hurt to *also* switch with a relay...

and there will be no safety ground to return the current to ground
when the energized wire melts its solder joint and falls on the
inside of the enclosure you're holding in one hand while your other
hand or foot is grounded to whatever. Do the EMTs know which
hospital you prefer or should they just get you to the nearest one?

Not if your real objective is electrocution or fire.

A common mistake that people make
when trying to design something completely foolproof
is to underestimate the ingenuity of complete fools.
-Douglas Adams
Active8

There's a reason engineering-types are often thought of as pessimists:
We always have to say "What if".
It's our job to consider worst-case conditions.