Connect 120 volt circuits to get 240 volts

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For faster charging when not at a public charger a portable way to get 240  
volts at a home or business that doesn't have 240 volt outlets is to pick o
ff two outlets that are wired to separate circuits on opposite sides of the
 240 volt power.  There is a commercial product for this and designs on the
 web.  I found this schematic.  

https://cdn.hackaday.io/images/2004701426644738630.png

I'm wondering if the two pole relays are needed on the input side.  Seems t
he issue is that without the input relays when you plug the unit into one o
utlet the path through the output relay coil can energize an exposed plug p
in.  But I don't see the need for two poles.  Running the 120 volt connecti
on through the input relay contacts on just one side of the output relay co
il will prevent the two inputs from being energized when only one is plugge
d in.  

Am I missing something or is this design a bit over complicated?  The only  
advantage I can see is that with the two pole relays a single stuck contact
 won't be dangerous.  In a one pole approach it can pass a dangerous voltag
e to the input plug pin.  But you can hear relays working so a stuck relay  
can be detected.  Also it has indicators on the inputs so you can tell the  
relay isn't clicking because of a failure rather than simply no voltage.  S
o this risk seems minimal.  

  Rick C.

  - Get 6 months of free supercharging
  - Tesla referral code - https://ts.la/richard11209

Re: Connect 120 volt circuits to get 240 volts
On 12/29/2018 02:28 PM, snipped-for-privacy@gmail.com wrote:
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It looks mad.

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Re: Connect 120 volt circuits to get 240 volts
On Saturday, December 29, 2018 at 2:58:35 PM UTC-5, bitrex wrote:
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240 volts at a home or business that doesn't have 240 volt outlets is to pi
ck off two outlets that are wired to separate circuits on opposite sides of
 the 240 volt power.  There is a commercial product for this and designs on
 the web.  I found this schematic.
Quoted text here. Click to load it
ms the issue is that without the input relays when you plug the unit into o
ne outlet the path through the output relay coil can energize an exposed pl
ug pin.  But I don't see the need for two poles.  Running the 120 volt conn
ection through the input relay contacts on just one side of the output rela
y coil will prevent the two inputs from being energized when only one is pl
ugged in.
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nly advantage I can see is that with the two pole relays a single stuck con
tact won't be dangerous.  In a one pole approach it can pass a dangerous vo
ltage to the input plug pin.  But you can hear relays working so a stuck re
lay can be detected.  Also it has indicators on the inputs so you can tell  
the relay isn't clicking because of a failure rather than simply no voltage
.  So this risk seems minimal.
Quoted text here. Click to load it

I always appreciate a well thought out criticism.  

  Rick C.

  + Get 6 months of free supercharging
  + Tesla referral code - https://ts.la/richard11209

Re: Connect 120 volt circuits to get 240 volts

Connect 120 volt circuits to get 240 volts

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It looks crazy.  

Are you trying to save wires from main circuit box to the garage, which are usually next to each other?  
Or are you trying to skip 240V circuit breakers and exposing the 120V breakers to 220V?

Don't forget J1772 are usually 240V 30A.  It will brow the 120V 15A immediately.



Re: Connect 120 volt circuits to get 240 volts
On 12/29/2018 03:40 PM, snipped-for-privacy@gmail.com wrote:
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IMO all designs that use AC line powered relays as some kind of "relay  
logic" to control their own line currents are mad and disasters waiting  
to happen.

I remember a number of years ago there was some guy who regularly posted  
line powered relay logic designs to control stuff in his  
serial-killer-looking barn at his serial-killer/cult headquarters farm  
(where wearing yellow aviator sunglasses is a requirement for male heads  
of household) or something. They were all mad, too

Re: Connect 120 volt circuits to get 240 volts
On Saturday, December 29, 2018 at 4:08:21 PM UTC-5, bitrex wrote:
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So you completely fail to understand the circuit?  Got it.  

  Rick C.

  +- Get 6 months of free supercharging
  +- Tesla referral code - https://ts.la/richard11209

Re: Connect 120 volt circuits to get 240 volts
On 29/12/2018 21:22, snipped-for-privacy@gmail.com wrote:
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The functionality of the circuit is orthogonal to its safety. The  
functionality is not in much question except with whether 1 or 2 pole  
relays are needed.

It will function.

It is not safe in my opinion. Several people have told you that.



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Re: Connect 120 volt circuits to get 240 volts
On Saturday, December 29, 2018 at 3:40:28 PM UTC-5, snipped-for-privacy@gmail.com wrote:
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Hmmm... auto chargers are not all J1772 and they can all be configured (all that I have seen) for a given current for each situation.  Even so, I'm not using a J1772.  Care to guess what I'm charging?  

  Rick C.

  -+ Get 6 months of free supercharging
  -+ Tesla referral code - https://ts.la/richard11209

Re: Connect 120 volt circuits to get 240 volts
On Saturday, December 29, 2018 at 1:21:38 PM UTC-8, snipped-for-privacy@gmail.com wrote:
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My Nissan Leaf, when i visit you?  I can't use your non-standard T-charger anyway.  Are you planing to down-grade your T-charger to 6KW (15A)?

The only reason i can think of is your builder is totally ignorance of EV and put the garage on far side of the main breaker.  In that case, the #10 or #12 wires would not be enough.  

My idiot rule to add to the NEC:  A garage should be connected to the main via 4 #6 or #8 wires.  440V should be optional.  I want 440V in my garage.

Re: Connect 120 volt circuits to get 240 volts
On 29/12/2018 22:40, snipped-for-privacy@gmail.com wrote:

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Dumb question from a Brit used to a different system:

Are you suggesting a new type of company transformer?

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Re: Connect 120 volt circuits to get 240 volts
On Saturday, December 29, 2018 at 2:52:24 PM UTC-8, Tim Watts wrote:
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440V (perhaps 3 phases) is available for certain industrial users in the US.  Hope it gets to residential users eventually.  240V is not enough for EV, or aluminum melter.  I want to charge up my EV and melt and cast aluminum.


Re: Connect 120 volt circuits to get 240 volts
On 29/12/2018 23:04, snipped-for-privacy@gmail.com wrote:
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Interesting. Thank you.

Yes, the whole EV thing is going to open a can of worms.

In the UK, we already have 240V (well 230V officially thanks to EU  
harmonisation, but it's really 240V most of the time) - and many of us  
have 100A supplies with 60A being the smallest domestic supply I've seen.

Even then, a dedicated EV charging circuit is likely to be 32A (one of  
our standard breaker ratings) but compared to a supercharger, it would  
still be slow.

We could get 3 phase supplies (although we'd need a new breaker panel  
design for that - UK domestic panels are tiny, we'd need to switch to  
industrial panels more like the US ones in size and layout).

But it's all a bit mute as we're hard on the line for power generation  
as it is thanks to the greens shutting coal power stations and NIMBYs  
rejecting new nuclear:

http://www.gridwatch.templar.co.uk/

A few years ago in a particularly cold winter, I saw that peak at over  
60GW demand for the UK.

Now we only have 50GW generating capacity assuming something doesn't go  
bang unexpectedly :(



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Re: Connect 120 volt circuits to get 240 volts
On Saturday, 29 December 2018 23:16:30 UTC, Tim Watts  wrote:
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We're stuck with 240v at anything from 40A to 100A incomers. 240v 100A is 24kW, not so good for small flat dwellers with only 40A = 9.6kW. Of course one could only use all of it to charge when there's no other draw.

To upgrade from there would require new underground feeds, 3 phases are generally not available at the incomer. And new incomer, new CU etc. And quite likely a major upgrade in the whole infrastructure.

We can surely have 240v 40A sockets without any new CU or incomer, and probably more. 100A car sockets would require demand management, which isn't hard to retrofit, it's just more equipment.


NT

Re: Connect 120 volt circuits to get 240 volts
On Saturday, December 29, 2018 at 6:16:30 PM UTC-5, Tim Watts wrote:
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 main via 4 #6 or #8 wires.  440V should be optional.  I want 440V in my ga
rage.
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e US.  Hope it gets to residential users eventually.  240V is not enough fo
r EV, or aluminum melter.  I want to charge up my EV and melt and cast alum
inum.
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In the US homes get 240 volts and anything in the last 50 years should have
 200 amps.  My family home built in '64 only has 100 amp service.  


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Here many units are 30 amps, but for Teslas you can get up to a 100 amp cir
cuit with the car drawing 72 amps.  That's a hefty load for sure and not st
rictly needed.  I'm presently still charging from 120 V, 15 amps with the c
ar drawing 12 (the US has an 80% factor for continuous loads).  Since I don
't drive much while here it has several days to charge before I leave typic
ally.  But since there have been times when I wanted to turn around and lea
ve again in less than 8 hours, something above the capacity of a 14-50 outl
et can be useful.  That requires a Tesla Wall connector which is the Tesla  
equivalent of a J1772 unit.  The J1772 can provide up to 80 amps to the car
, so if anyone wants to, they can do the same charging on either unit.  

All of this is fairly slow compared to a Supercharger which I don't think y
ou can get.  80 amps is about 20 kW while a Supercharger is 120 kW.  

The real issue is charging at home means you don't really have to think abo
ut it.  Connect the car when you get home and it will always be full. Never
 visit a gas station again... unless you want coffee or a bathroom.  lol  


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I've heard they are rather small having as few as four circuit breakers.  I
've seen ancient fuse panels here that have just four fuses.  I guess maybe
 heavy loads are less common there?  


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I understand you get power from France when you need it.  DC lines under th
e channel.  No?  

  Rick C.

  --- Get 6 months of free supercharging
  --- Tesla referral code - https://ts.la/richard11209

Re: Connect 120 volt circuits to get 240 volts
On Sunday, 30 December 2018 01:20:09 UTC, snipped-for-privacy@gmail.com  wrote:
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Old fuseboxes can have as few as 4 circuits, with all the sockets on 2 circuits.


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Sockets are mostly on 30/32A circuits. Immersion heaters don't exceed 3kW. Showers are 7-10kW. Ovens vary widely.


NT

Re: Connect 120 volt circuits to get 240 volts
On Sun, 30 Dec 2018 05:15:48 -0800 (PST), snipped-for-privacy@gmail.com wrote:

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Due to the large fuses feeding the sockets, you need to have smaller
fuses installed in each mains _plug_, so the distribution panel can be
very small, when the fuse selectivity is distributed into all plugs.


Re: Connect 120 volt circuits to get 240 volts
On Sun, 30 Dec 2018 05:15:48 -0800 (PST), snipped-for-privacy@gmail.com wrote:

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This is our breaker box:

https://www.dropbox.com/s/i96u0iql5qlrlev/Breakers.JPG?dl=0

The main service is 120-0-120 at 125+125 amps. Most outlets are 120V,
but a few are 240.

We don't have air conditioning, and heating/hot water/stovetop/clothes
dryer are natural gas, so our power feed is fairly small. I don't
think we have tripped a breaker since we moved in in 1993.



--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: Connect 120 volt circuits to get 240 volts
On Sunday, 30 December 2018 17:30:21 UTC, John Larkin  wrote:
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New ones here look a bit like that. Old ones are far more basic, typically just 4-8 wire fuses and a switch, all in bakelite on wood. The 8 way here is typical:
http://wiki.diyfaq.org.uk/index.php/CU

A 1930s one, 2 circuits, dual pole fusing:
http://wiki.diyfaq.org.uk/index.php/Changing_a_consumer_unit
Not many of those left in the wild. Pre-1960s wiring here is not at all ok.


NT

Re: Connect 120 volt circuits to get 240 volts

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Are you still using ring mains even in new buildings ? Of course the
distribution panel would be minimal for ring mains.

In continental Europe 230/400 V are often available sometimes even in
apartments.. The smallest fuses are 3 x 16 A (10 kW) continuous.
Larger currents are available, but not so common.

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At least before Brexit, there are HVDC links across the channel just
for that reason.

At least in smaller countries with limited average daily driving
distances, one big nuclear rector should be able to support one
million EVs.



Re: Connect 120 volt circuits to get 240 volts
On Sunday, December 30, 2018 at 12:26:44 AM UTC-5, snipped-for-privacy@downunder.com w
rote:
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e main via 4 #6 or #8 wires.  440V should be optional.  I want 440V in my g
arage.
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he US.  Hope it gets to residential users eventually.  240V is not enough f
or EV, or aluminum melter.  I want to charge up my EV and melt and cast alu
minum.
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.
  
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I'm pretty sure existing generation capacity is adequate for a very large n
umber of EVs.  The fast DC chargers are only needed for the relatively few  
cars that are on trips away from home and the small proportion of EVs that  
don't have home charging.  In general fast DC and other day time charging w
ill be a small proportion of the total EV charge load.  Most of it will be  
done from home since that is most convenient and cheapest.  

Once EVs become a significant factor in the load on the electrical grid pla
ns will be in place to do two things.  First there will be time control ove
r charging controlled by the grid.  Second, to promote participation in thi
s charging time control the reduced cost of generating this power will be s
hared with the EV owners.  

  Rick C.

  ---+ Get 6 months of free supercharging
  ---+ Tesla referral code - https://ts.la/richard11209

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