Is it safe to use a "quad" breaker to supply NEMA 6-50 outlet for EV charging?

Question

I recently acquired a new EV and I'd like to upgrade my electrical system to include a NEMA 6-50 outlet (my car charger uses this one as opposed to the more popular 14-50) to provide faster, level 2 charging. I've received inconsistent information from a variety of local electricians on the best approach since my main panel (200 amps) is currently full.

Many have suggested I use a "quad breaker" to supply the new outlet. This is by far the cheapest option (quotes I've received are $350-$750). A few others, however, have said that I will "burn the panel" if I use a quad breaker, and "those other electricians are just looking to make a quick buck". The alternative setup suggested would be a new dedicated sub panel for the EV charger (quotes are around $2500 for this setup).

I'm honestly not sure who is looking to make a buck here. I'm also not looking to cut corners. I just want to do what is considered appropriate and safe.

Answer 1

There are a few different issues here:

Service Capacity

Any time you make a large increase in electricity usage you need to do a Load Calculation. This takes into account many things, including:

• Size of the building
• Major fixed appliances such as water heater, EV charging, clothes dryer, oven, cooktop, etc.
• Required kitchen, bathroom and possibly other circuits
• HVAC - largest of Heating or Air Conditioning, since they don't run at the same time

It is a relatively complex thing, as it has a number of things that increase or decrease the calculation in possibly unexpected ways.

It is NOT:

• Add up breaker handles - way too high (except in the case of some very small subpanels with specific dedicated circuits)
• Electric bill average usage - way too low
• Electric bill peak usage - that gets closer, but needs to be considered over a long period of time and even then may not be close to the real number
• Guessing/estimating

Google: NEC Load Calculation to get details.

So the first step is to take your service capacity (typical is 200A, but sometimes more and often less, particularly in older houses - presumably you have 200A service based on the main breaker) and subtract the current Load Calculation and see what is left. Is that enough for 240V @ 50A? If so, great, you can do your 6-50. Is it enough for 240V @ 40A? 30A? 20A? Any of those can be made to work and provide enough power for most people to charge EVs most of the time.

If your Load Calculation shows you already oversubscribed then you have to deal with that ("heavy up" or load shedding) first. If your Load Calculation doesn't have quite enough then load shedding is likely the way to go unless you have other reasons for a "heavy up".

Panel Space

Your panel is full. Almost every breaker already has half-size (tandem/double-stuff) breakers. Most new circuits require AFCI (almost always best in the panel), GFCI (OK at point of use for 120V but 240V always in the panel) or both. AFCI and GFCI breakers are generally (there are some exceptions) available only in full-size breakers. So even if you can manage to squeeze in this one additional circuit, you really are running out of space and a subpanel may make a LOT of sense. A subpanel doesn't increase your service capacity but it does let you put in more breakers/circuits, including full-size breakers where needed.

As far as I am concerned, if the panel manufacturer offers a legitimate UL or ETL listed 50A quad (probably 50A inner pair, 15A or 20A outer pair) that's perfectly safe. But it won't have GFCI.

Receptacle vs. Hardwired

You are correct that a 6-50 is fine for EV charging as there is no need for the neutral of a 14-50. However, a receptacle for almost any use now requires GFCI. That does depend on NEC version (I think it started in 2020 and states vary quite a bit in their adoption time of each NEC version). In addition, some jurisdictions have exceptions that may apply. So you need to find out your specific local requirements.

There are three advantages of hardwired over receptacle for EV charging:

• No GFCI required. The EVSE and car already take care of that, so no GFCI is needed in the panel/breaker.
• Heavy-duty 50A receptacles are expensive. Due to the continuous (hours at a time) nature of EV charging, heavy-duty really is recommended.
• Many EVSE devices (e.g., Tesla Wall Charger) are simply not designed for plug/cord connection.

Plug/cord/receptacle makes sense if you have to move things. It doesn't make sense for EVSE that is installed once and left in place for years at a time.

If you say "I have a travel charger and want to plug that in", my answer is to keep that in the trunk or frunk for when you are on the road visiting someplace that doesn't have any hardwired EVSE.

Answer 2

You might be able to use a quad breaker in that panel to feed the charger, if you add more parts, or if you give up the plug-in capability and use a hard-wired charger.

An outlet for an EV may require a GFCI breaker if your local code authority requires it, and more authorities are requiring it. Because it's in a garage, and garage outlets usually need to be GFCI protected, and GFCI outlets don't come in NEMA 6-50 or 14-50. GFCI breakers don't come in quad configurations.

It would be possible to start feeding the plug-in charger using a quad breaker in this panel, but you'd have to put a small subpanel or "spa panel" between this panel and the charger's outlet, and put the GFCI breaker in the subpanel. More expense this way, but it can be fed by a quad from this panel, assuming the panel officially allows quads.

EV chargers that are hard-wired to a junction box, not using a plug and outlet, do not require a GFCI breaker. This is because the car and charger are the GFCI. If you used a hard-wired charger, you can use a quad breaker (as long as the portion of the breaker you will use is is common trip). Don't just cut the plug off: the instructions need to tell you how to hard-wire the charger before you can "legally" hard-wire it and keep your insurance company happy.

Here are a few other things to consider that might ease the requirements of your EV setup and get you charging:

• You need to do an NEC load calculation to determine if your existing electrical service and breaker panel has enough electrical room for the power pulled by the EV charger.

• Many people are quite able to get by with much less EV charging capability than the 50 amps (actually 40 amps due to the code-required 80% de-rate) the charger can do. If you regularly drain the whole car battery and need to charge it fully in a few hours at home, you'd need the full 50 (40). But if you only use 5-10% of the battery, or you can let the car sit overnight for a charge, you may be able to get by with a 20-amp (16 de-rated) charging level.

• Some EV chargers can determine how much power is being drawn by other devices in the house and reduce the EV charge rate accordingly. This can get around a too-small load calculation without the "heavy-up" increase in house electrical service that a non-adjustable EV charger would require. So if the oven, the pool heater, and the AC are running, the car gets a slow charge. But when these other loads are off, the car gets a fast charge.

Answer 3

A quad breaker will not harm your panel as long as you keep an eye on two things:

1. Your panel must support quad breakers. Most current panels do, the one main exception being QO (which inherently has less need for quads because their breakers are smaller so they can fit more spaces in the same area as other brands).

2. You must obey any “stab limits” your panel gives. The panel will say something on the label like “no more than 125A per bus stab”. The breakers connect to tabs of metal that are perpendicular to the bus bars, and, generally being smaller than the bus bars, are often not rated to pass through the full service size. In your third row from the top (where half of a double-pole 40A is across from the bottom half of a 30/50 quad) you have 120A on one stab, which is probably OK but might be right at the limit. You might have to shuffle breakers around to stay within limits - simply replacing the double-pole 40A with a 40/40 quad might exceed the limits.