Do It Yourself: 240v from two 120v sources

nsayer said:

Let's not forget, a hot-neutral swap will cause a two-relay design to present 120 volts to a 240 volt device. That may not be unsafe from a hazard to life perspective, but it may result in equipment damage.

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Yes, I think everybody gets that. The contention was the "safety" aspect, and again, I don't see Phil's design (which I built long ago) as unsafe. Yours is more "complete", and may save some unpleasantness to some component, but Phil's is not unsafe to humans.

Phil's prevents the virtual neutral problem.

I'm not sure I'm willing to concede that that is the only danger to humans that is worthy of prevention. But I'm content to agree to disagree.

And besides, "safety" encompasses not just injury prevention, but damage to property as well.

If you are using this on an EVSE, there is no risk of equipment damage should it run on 120v. It's also highly unlikely that low voltage could damage ANY equipment.

People: Do not subscribe to the FUD, there is nothing wrong with your 2-relay design, and no need to change it. There's been quite a few of these built and thousands sold of a similar design (Quick220) that passed UL testing procedures. Most UL tests are quite stringent!

You should never open any electrical equipment until ALL connections are disconnected. Nsayer's "corner case" wouldn't even apply.

The design of safety systems is to protect uninformed public, not a qualified professional. If you consider yourself such and you start working on equipment still energized, then you are definitely not!

-Phil

Ingineer said:

If you are using this on an EVSE, there is no risk of equipment damage should it run on 120v. It's also highly unlikely that low voltage could damage ANY equipment.

People: Do not subscribe to the FUD, there is nothing wrong with your 2-relay design, and no need to change it. There's been quite a few of these built and thousands sold of a similar design (Quick220) that passed UL testing procedures. Most UL tests are quite stringent!

You should never open any electrical equipment until ALL connections are disconnected. Nsayer's "corner case" wouldn't even apply.

The design of safety systems is to protect uninformed public, not a qualified professional. If you consider yourself such and you start working on equipment still energized, then you are definitely not!

-Phil

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Go look at the Quick220 patent. It's not the same design as yours. Saying that their UL approval has anything at all to do with your design is disingenuous at best.

Suggesting that qualified professionals don't need or use safety systems (as opposed to the "uninformed public") is downright laughable.

No qualified professional would knowingly work on energized equipment. Safety systems are designed to prevent hazardous ambiguities. And it's defense in depth - something that is easily worth the extra $15.

nsayer said:

Go look at the Quick220 patent.

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What are the particulars of that one?

It was a few pages back.

https://www.google.com/patents/US5977658" onclick="window.open(this.href);return false;

Their design is a single 208/240 relay wired the same way as the "third" relay of my design.

I designed mine before I discovered their design. The only weakness is that they're not testing the neutrals. You can argue that that's not necessary. I don't have nearly as good a rebuttal for that, except that if the neutral is not working there may be other problems hiding.

nsayer said:

I don't have nearly as good a rebuttal for that, except that if the neutral is not working there may be other problems hiding.

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Fair enough.

I took a moment to read the Quick220 patent. Even they called out the same objection I did:

If, the user proceeds as in the previous paragraph, but connects the second input plug 10B to another 120-volt receptacle (not shown) that is wired to the same end of secondary winding 38 of distribution transformer 36 as is first receptacle 44A, the resulting voltage between line voltage conductors 12A and 12B and, hence, control terminals 20A and 20B will be zero. The switching device 18 will not close, and the line voltage conductors 12A and 12B will remain electrically isolated from output conductors 24A and 24B. Similarly, if there is line voltage on either of conductor 24A or 24B, but not on the other, switching device 18 will not close, and the line voltage 12A and 12B will remain electrically isolated from output conductors 24A and 24B. This isolation is a desirable feature of the invention: power is isolated from the output receptacle 28 and the electrical load 46 until input plugs 10A and 10B are properly connected to appropriate 120-volt conductors which are 180 degrees out of phase, producing the desired 240-volt output. This eliminates potential equipment damage or electrical shock to the user, which may happen if either output conductor 24A or 24B is electrically connected to power and the other is not.

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Q.E.D.

nsayer: I would be interested if you would comment on the advisability of:

1) On a regular basis using any device like yours in an area which would definitely benefit from GFCI protection at either the two receptacles used (e.g. a concrete floored basement garage that is prone to becoming damp when it rains)?

2) On a regular basis using any plug-in EVSE on a single non-GFCI protected receptacle in a similarly hazardous area?

MikeD said:

nsayer: I would be interested if you would comment on the advisability of:

1) On a regular basis using any device like yours in an area which would definitely benefit from GFCI protection at either the two receptacles used (e.g. a concrete floored basement garage that is prone to becoming damp when it rains)?

2) On a regular basis using any plug-in EVSE on a single non-GFCI protected receptacle in a similarly hazardous area?

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Well, you can't use this device on GFI outlets. I would advise against removing GFI protection from outlets so that you can use this device.

I don't believe they sell GFI equipped 220 outlets. They do make GFI equipped ganged circuit breakers. You could use that to add GFI protection to this device. Remember that the GFI only protects in the downstream direction. It won't offer any proaction from malfunctions upstream. That's why building codes call for GFI outlets in bathrooms, kitchens and garages, where damp conditions are expected. The concern is plugging and unplugging the 120 cables of the "quick220" device itself when you're standing on a damp floor. There can be no GFI protection for that operation, because the device is incompatible with GFI outlets.

EVSEs are required by the J1772 specification to include their own GFI circuitry. So EVSEs are safe to use in all weather, HOWEVER, the GFI typically only protects from the J1772 cable to the car. You must follow the manufacturer's/builder's recommendation as to how to treat the chassis of the device and its electrical connection, as those are outside the scope of GFI protection. That said, standing on a wet floor and manipulating a 240 volt plug is not a great idea. If you had to do so you would be well advised to shut off the breaker and/or unplug the "quick220" device first.

nsayer said:

EVSEs are required by the J1772 specification to include their own GFI circuitry.

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Are you sure this is true? Rich Rudman claims it is not a requirement and that if he doesn't have to add it to get his Manzanita Micro P3 EVSE NRTL listed he will not do so.

One of the reasons I like Tony's/Quick Charge Power's JLONG (J1772 extension cord) is that it helps provide more of your length in GFCI. So for example if you use a Quick220 in the house (because most garage receptacles should have GFCI) you may normally need an extension cord to get the EVSE close enough to the car but if instead you keep the EVSE in the house as well and use the JLONG to get to the car the entire length outside the house is GFCI protected by the EVSE.

QueenBee said:

nsayer said:

EVSEs are required by the J1772 specification to include their own GFI circuitry.

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Are you sure this is true? Rich Rudman claims it is not a requirement and that if he doesn't have to add it to get his Manzanita Micro P3 EVSE NRTL listed he will not do so.

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Well, I don't know what certifying organizations (like UL) will care about, but in looking at the October 2012 revision of the J1772 PDF I see a GFI in the diagrams on page 26 and 32 (which depict a L2 and a L3 EVSE/EV block diagram).

Additionally, on page 57 there's a note that talks about an EVSE experiencing an error condition "such as a ground fault."

The document I have doesn't quite explicitly state a GFI requirement, but it's heavily implied.

That's certainly enough for me to suggest that an EVSE that does not include a GFI is not fully compliant with the specification. And building an EVSE without a GFI would, IMHO, be a stunningly bad idea.

nsayer said:

QueenBee said:

nsayer said:

EVSEs are required by the J1772 specification to include their own GFI circuitry.

Click to expand...

Are you sure this is true? Rich Rudman claims it is not a requirement and that if he doesn't have to add it to get his Manzanita Micro P3 EVSE NRTL listed he will not do so.

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Well, I don't know what certifying organizations (like UL) will care about, but in looking at the October 2012 revision of the J1772 PDF I see a GFI in the diagrams on page 26 and 32 (which depict a L2 and a L3 EVSE/EV block diagram).

Additionally, on page 57 there's a note that talks about an EVSE experiencing an error condition "such as a ground fault."

The document I have doesn't quite explicitly state a GFI requirement, but it's heavily implied.

That's certainly enough for me to suggest that an EVSE that does not include a GFI is not fully compliant with the specification. And building an EVSE without a GFI would, IMHO, be a stunningly bad idea.

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Could not agree with you more. I tried really hard to convince him of that and that he should be warning his customers so that if they are concerned with safety they can at least install a GFCI breaker.

GFCI is required by NEC 625.22 and UL 2231. It is mentioned in SAE J1772. Not including it in a product sold to the public is irresponsible.

QueenBee said:

Are you sure this is true? Rich Rudman claims it is not a requirement and that if he doesn't have to add it to get his Manzanita Micro P3 EVSE NRTL listed he will not do so.

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chris1howell said:

GFCI is required by NEC 625.22 and UL 2231. It is mentioned in SAE J1772. Not including it in a product sold to the public is irresponsible.

QueenBee said:

Are you sure this is true? Rich Rudman claims it is not a requirement and that if he doesn't have to add it to get his Manzanita Micro P3 EVSE NRTL listed he will not do so.

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Would NEC be happy with a GFCI circuit breaker or does it require the EVSE it self to also provide it? I have a feeling he'll never get it NRTL listed but glad to see that they'll require it.

I tried very hard to convince him to warn people that he was selling what I consider an unsafe product and to add GFCI but I can understand why he doesn't want to advertise that his product is unsafe and to make it safe would cost significantly more (240 volt GFCI breaker) than it already does compared to his competitors safe products. As to why he doesn't want to add GFCI I have no idea...

Adding a GFI circuit to an EVSE doesn't cost a lot. It's a single chip, a handful of discrete components and a CT coil. It's like an auto maker complaining that it's too expensive to add brakes to an EV. Sure, you could make a car that stops with regenerative braking entirely, but there's just no way anyone would call the result roadworthy.

The NEC isn't concerned with anything that plugs in. That's why UL gets involved. The NEC talks about EVSEs because some of them are hard wired. In principle a hard wired EVSE with a GFI breaker would be ok.

I don't know what UL's stand is. I'm not sure you could pass by just documenting a requirement for a GFI breaker on the socket.

Nope it is required to be in the EVSE for both L1 and L2 within 18" of the plug (if corded). Adding GFCI is not very costly, the OpenEVSE design is about $1 for components and $12 for the coil...

QueenBee said:

chris1howell said:

GFCI is required by NEC 625.22 and UL 2231. It is mentioned in SAE J1772. Not including it in a product sold to the public is irresponsible.

QueenBee said:

Are you sure this is true? Rich Rudman claims it is not a requirement and that if he doesn't have to add it to get his Manzanita Micro P3 EVSE NRTL listed he will not do so.

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Would NEC be happy with a GFCI circuit breaker or does it require the EVSE it self to also provide it? I have a feeling he'll never get it NRTL listed but glad to see that they'll require it.

I tried very hard to convince him to warn people that he was selling what I consider an unsafe product and to add GFCI but I can understand why he doesn't want to advertise that his product is unsafe and to make it safe would cost significantly more (240 volt GFCI breaker) than it already does compared to his competitors safe products. As to why he doesn't want to add GFCI I have no idea...

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chris1howell said:

Nope it is required to be in the EVSE for both L1 and L2 within 18" of the plug (if corded).

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I always wondered why the cords were so short. I've been putting, like, 6 foot SOOW cables on mine, but I guess I'm not submitting mine to UL any time soon.

In "Feature Comparison" advertising I notice Siemens touts their VersiCharge EVSE (along with Schneider EVlink) as having a "UL Listed 5 mA CCID" feature, but lists GE Wattstation, Leviton Evr-Green 160, and Aerovironment EVSE-RS EVSE models as NOT having that feature.

It may be that those three models have a CCID (Charging Circuit Interrupting Device) feature, but at a higher threshold than the "Class A" 5 ma +/- 1 ma level. If so, a higher threshold CCID feature would seem to me to not be quite as safe.

Rather than get lost in discussion about the above or other issues, I want to applaud what nsayer had to say about the important safety value a GFCI protected outlet/circuit provides for plug-in EVSEs in damp conditions.

MikeD said:

In "Feature Comparison" advertising I notice Siemens touts their VersiCharge EVSE (along with Schneider EVlink) as having a "UL Listed 5 mA CCID" feature, but lists GE Wattstation, Leviton Evr-Green 160, and Aerovironment EVSE-RS EVSE models as NOT having that feature.

It may be that those three models have a CCID (Charging Circuit Interrupting Device) feature, but at a higher threshold than the "Class A" 5 ma +/- 1 ma level. If so, a higher threshold CCID feature would seem to me to not be quite as safe.

Rather than get lost in discussion about the above or other issues, I want to applaud what nsayer had to say about the important safety value a GFCI protected outlet/circuit provides for plug-in EVSEs in damp conditions.

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Thanks.

I am not sure what the controlling document for EVSE GFI sensitivity is. Chris has stated, and designed OpenEVSE to, a 20 mA standard. I built one for 10 mA, but my wife's Volt trips at that rate just often enough to be annoying. I've personally decided to split the difference and design going forward for something like 15 mA or so.

My assumption is that the switching supply startup in the Volt has an inrush characteristic that momentarily causes an imbalance of just over 10 mA. I'm not such an expert at analog and power electronics design analysis to understand how that might happen. But it's suggestive to me that if Siemens is bragging about 5 mA sensitivity, they're going to piss off a lot of Volt owners unless they're being sophisticated about intensity vs duration of the trip (OpenEVSE and the Hydra don't - any excessive excursion causes a fault response).