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I'm installing an EV charger but my panel is only big enough to run either the dryer or the EV charger at the same time. So I have a current sensor on the dryer line so that when the dryer is running the EV charger circuit opens.

The EV charger is 240VAC, 24A, on a split phase circuit. I have a crydom SSR (rated to 50A) and heat sink but it's single pole. Is it safe for me to just break a single phase on the EV circuit when I want to disconnect the charger? (It's currently working with a standard dual pole power relay, but the panel is in my bedroom and the click on/off is really loud and keeps waking the baby).

Here is the only info I have on the EV charger circuit:

EV Charger Circuit

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    While what you are doing is conceptually 100% fine, whether the implementation is proper or not is unknown. If you ever have an electrical fire or similar problem, the insurance company may invalidate your coverage based on this unlisted equipment even if the equipment is not the cause of the fire. There are commercial listed/certified/tested systems of this type available, and the cost may be worth it even if your homebrew solution is functionally identical.
    – manassehkatz-Moving 2 Codidact
    Commented Nov 21, 2023 at 23:35
  • Note that you cannot use a random SSR or relay for this -- you'll need something like a RIB or a general-purpose contactor that's listed to UL 508 and rated for the load in question.
    – ThreePhaseEel
    Commented Nov 22, 2023 at 2:51
  • @ThreePhaseEel the one I have is rated to 50A (sensata.com/sites/default/files/media/documents/2018-04-25/…)
    – InternationalCodingGuru
    Commented Nov 22, 2023 at 3:33
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    @WiseShepherd -- the issue isn't the amp rating, it's that it's only UL Component Recognized (RU = Rather Useless to us) for use in a larger UL-Listed product vs being fully UL Listed for direct installation in the field
    – ThreePhaseEel
    Commented Nov 22, 2023 at 5:01

3 Answers 3

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Instead of dealing with turning on and off the car charger you can opt for a smart EVSE with current probes that go onto the feed of the panel.

That way the EVSE can throttle charging when other loads are taking up capacity.

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Ah, the things people do to charge EVs. If you actually run through your NEC 220.82 Load Calculation, you'll see that dryers come in only at 40%. EV loads come in at 125% (ask your municipality) so knocking out a dryer doesn't quite create the headroom needed to charge an EV.

However, your project would be much better served by an EVEMS system made specifically for this purpose, such as the Wallbox Pulsar Plus with Power Boost, or Emporia Load Management bundle. Trying to hork something together with electronics parts is tempting, but you will have a lot of explaining to do when it has a safety problem. This work is already done for you, and done well.

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Assuming you are also using a receptacle because it's the usual for this sort of weird DIY style charging setup, it's not particularly dangerous to break just one side of the circuit, but it's not particularly safe either. If you have one side open, the EVSE or the outlet for it can potentially appear to be dead and off due to not operating while also being live thanks to having 120V on one side. It's not an accident that equipment hooked to 240V almost always has a two pole contactor. Consider spending the $100 on a proper DPST SSR for your application.

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