Switch EV Load using Contactor

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kwired said:
Wouldn't a contactor with NC contacts, changeover or reversing contactor even a transfer switch, any those with probably a 100 amp rating needed cost enough that you maybe just consider upgrading service to 200 amps?
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A three-pole normally open 100 amp contactor and a small junction box to put it in is probably going to cost you around $200.
 
Tarmac said:
but this will add an extra $20K
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$20,000 for a 200 amp single phase residential service?

There are people doing whole houses for less than that.

There are only about $600 in materials involved in a 200 amp residential service
 
Joethemechanic said:
$20,000 for a 200 amp single phase residential service?

There are people doing whole houses for less than that.

There are only about $600 in materials involved in a 200 amp residential service
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I would bet the utility is going to charge more than $600 to change the service. There might also be other issues have to be dealt with if the service is changed out. 20,000 seems like a lot to change from 100 to a 200 amp service, but I would not discount it entirely.
 
petersonra said:
I would bet the utility is going to charge more than $600 to change the service. There might also be other issues have to be dealt with if the service is changed out. 20,000 seems like a lot to change from 100 to a 200 amp service, but I would not discount it entirely.
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If it really is 20k I would have installed a propane steam generator. This is what happens when customers buy the wrong stuff and expect you to make it work.

Even if you make it work, and the customer later decides he wants to charge his Teslas while taking a steam bath, or he has a friend who criticizes the setup, he will immediately forget it was his idea and badmouth you
 
petersonra said:
A three-pole normally open 100 amp contactor and a small junction box to put it in is probably going to cost you around $200.
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The discussion subject was for a normally closed contactor though.

Definite purpose or IEC contactor maybe only $200 for certain ones. 100 amp NEMA contactor puts you in size 4 and $200 isn't even close on those. NEMA size 4 pump panel last purchase for me was maybe around $3000. And normally I can buy the whole pump panel for less than I can buy a replacement contactor for it.
 
Re: "solid-state, high-current, NC relays are much more readily available"

SSRs have an appreciable voltage drop that's specified in the data sheet as a maximum. It shouldn't be an issue for the chargers or generator, but does mean that the SSRs will dissipate a lot of heat. You would need heat sinks and a fan to keep them happy. I've used them to control branch LED lighting circuits that only draw a few amps. I use a large metal junction box as their heat sink and it gets gets warm so the "ambient" temperature inside the box can reach 40 degrees C. That affects the choice of wiring to maintain code compliance.
 
Tarmac said:
Residential client has a dedicated 90 Amp service that is currently being used exclusively to power two Tesla chargers. Tesla chargers draw maximum of 240V, 72A using 3-wire (L1, L2, ground).

I need to install a 240V, 68A steam generator that requires a 240V / 90 Amp dedicated circuit (L1, L2, ground). The steam generator has a separate control pad that is powered directly from the steam generator.

The steam generator is used 20 minutes a day and when it's in use, I need to cut power to the Tesla chargers.

Can I use a NC contactor in front of charger junction box to cut power to the Tesla chargers whenever the steam generator is in use? I'd be relying on the current to the steam generator cutting out the EV current before tripping the main breaker.

Here's a circuit drawing.

Thoughts on this aappro
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Tarmac said:
Residential client has a dedicated 90 Amp service that is currently being used exclusively to power two Tesla chargers. Tesla chargers draw maximum of 240V, 72A using 3-wire (L1, L2, ground).

I need to install a 240V, 68A steam generator that requires a 240V / 90 Amp dedicated circuit (L1, L2, ground). The steam generator has a separate control pad that is powered directly from the steam generator.

The steam generator is used 20 minutes a day and when it's in use, I need to cut power to the Tesla chargers.

Can I use a NC contactor in front of charger junction box to cut power to the Tesla chargers whenever the steam generator is in use? I'd be relying on the current to the steam generator cutting out the EV current before tripping the main breaker.

Here's a circuit drawing.

Thoughts on this approach?
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I would ask the local AHJ if you could install a relay contact with the low voltage wire that runs from the EV charger to the EV that would stop the charger when the steam generator is started. Of course EV charger manufacturer might deny warranty claims any time that you make a change. Do most EV chargers automatically restart if power is lost or turned off a while ?
 
I'd use two of these, https://www.supplyhouse.com/Square-...RVcqLIjqQWL2kI2h4iYZPHU-1gSuO6YkaAkseEALw_wcB, wire the coil of each through an NC contact on the other, to a octal base cube relay, and install a digital fan timer in the bathroom. Have the digital fan timer trigger the cube relay, with the charger contactor on the NC contact of the cube relay, and the steam shower contactor coil on the N.O. contact. Throw them in a nema 1 cabinet mounted with some rubber pads between the cabinet and the mounting surface to minimize transmission of vibration. They kick the fan timer on for 20-30 min when running the steam shower, and when they are done it switches back to powering the tesla chargers.
 
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