14-50 on 100 amp breaker? Ok to use?

[Blacktes24]

Ok I want to bump this thread one more time and ask a question.... I know the 14-50 outlet is commonly sold adapter for the mobile connector and it's mainly because that is what is most widely used in the US in RV parks, campgrounds and such. I know most of the RV outlets are not 50 amp breakers. Usually 100amp breakers. So is it really that important to ONLY use a 50amp breaker???? I will install one and I've not even been using it as I've got by fine with 110 and supercharging on trips but just genuinely am curious and will install a 50amp breaker but I just can't see how it is that critical....

 

[3sr+buyer]

If the circuit has a 100A breaker, all of the wiring and stuff on it must be 100A capable.

Note that if the outlet is only 50A capable, but something plugged into it starts drawing more than 50A, that could be bad at the outlet.

 

[davewill]

... I know most of the RV outlets are not 50 amp breakers. Usually 100amp breakers. ...

I doubt this most seriously.

 

[stopcrazypp]

Ok I want to bump this thread one more time and ask a question.... I know the 14-50 outlet is commonly sold adapter for the mobile connector and it's mainly because that is what is most widely used in the US in RV parks, campgrounds and such. I know most of the RV outlets are not 50 amp breakers. Usually 100amp breakers.

Are you sure about that? The RV panel is 100A, but for the 14-50 socket it is a 50A breaker. Example here:

RV Electricity – Pedestal power basics

So is it really that important to ONLY use a 50amp breaker???? I will install one and I've not even been using it as I've got by fine with 110 and supercharging on trips but just genuinely am curious and will install a 50amp breaker but I just can't see how it is that critical....

If you use a 100A breaker then if you put a 100A load on it, the wiring and outlet will burn out well before the breaker trips if it wasn't rated for it. I doubt the wiring you have is rated for 100A, and if it's a 14-50 socket it would not be rated for 100A either even if your wiring was. That's pretty much the situation the code is trying to prevent.

Note if your local code doesn't need a GFCI breaker (this was introduced in NEC 2017), then a 50A breaker is only $10-20, hardly worth handwringing about, and pretty trivial to swap. If you need GFCI, that's another story (as mentioned it's more like $100).

 

[DiyEvRepair]

Breaker must be 50A otherwise the breaker is not protecting the outlet, which is only rated for 50A.

 

[Gauss Guzzler]

I know most of the RV outlets are not 50 amp breakers. Usually 100amp breakers.

Yeah, no. You do not know that. There are no public RV outlets on 100A breakers. Anywhere. Ever.

 

[Blacktes24]

Yeah, no. You do not know that. There are no public RV outlets on 100A breakers. Anywhere. Ever.

Ok well a new one i just went and looked at that was just installed to code today was 100 amp dual pole breaker and hooked right to the camper.....

 

[Blacktes24]

Can anyone tell me what this is????

 

[stopcrazypp]

Ok well a new one i just went and looked at that was just installed to code today was 100 amp dual pole breaker and hooked right to the camper.....

Are you sure you aren't looking at the main panel breaker instead of the subpanel that the actual outlet is connect to?

 

[Blacktes24]

Are you sure you aren't looking at the main panel breaker instead of the subpanel that the actual outlet is connect to?

yes i am sure.

 

[stopcrazypp]

yes i am sure.

If you can get your local inspector to sign off on using a 100A breaker for a NEMA 14-50 and your existing wiring (sounds like that's what you're saying, that whatever code version you are on locally allows that) then you don't really have to ask here right? If anything happens you have complied with your local inspection. The safety risks people have already mentioned previously, so it's up to you to make that decision (and the costs again is around $10-20 for a regular 50A breaker, around $100 for GFCI 50A breaker maybe more).

In case you are interested in the NEC, I looked up most of the relevant portions (although may not be comprehensive):

240.4 Protection of Conductors
Conductors, other than flexible cords, flexible cables, and fixture wires, shall be protected against overcurrent in accordance with their ampacities specified in 310.15, unless otherwise permitted or required in 240.4(A) through (G).

https://up.codes/viewer/california/ca-electric-code-2019/chapter/2/wiring-and-protection#240.4

Just looking it up, in the US NEC, 100A requires 3 AWG minimum wiring:
https://www.usawire-cable.com/pdfs/nec ampacities.pdf

The beefiest 14-50 outlet out there is rated for up to only 4 AWG (code requires following instructions of listed equipment):
Straight Blade Devices, Receptacles, RTP, Industrial Grade, 3-Pole 4-Wire Grounding, 50A 125/250V, 14-50R, Black, Single Pack. | HBL9450A | Wiring Device - Kellems

110.3(B) Installation and Use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.

NEC 110.3(B) and The Intermixing of Circuit breakers.

Seems pretty hard to get a code compliant 100A breaker used with 14-50, at least according to latest code.

There are certain exceptions, like for example welders, which can use a larger breaker (200% of device and conductors):

630.12 Overcurrent Protection

Overcurrent protection for arc welders shall be as provided in 630.12(A) and (B). Where the values as determined by this section do not correspond to the standard ampere ratings provided in 240.6 or where the rating or setting specified results in unnecessary opening of the overcurrent device, the next higher standard rating or setting shall be permitted.
(A) For Welders

Each welder shall have overcurrent protection rated or set at not more than 200 percent of I1max. Alternatively, if the I1max is not given, the overcurrent protection shall be rated or set at not more than 200 percent of the rated primary current of the welder.
...
(B) For Conductors

Conductors that supply one or more welders shall be protected by an overcurrent device rated or set at not more than 200 percent of the conductor ampacity.

https://up.codes/viewer/california/ca-electric-code-2019/chapter/6/special-equipment#630.12

You obviously aren't using this outlet for a welder though, so that exception goes out the window. Same deal with jurisdictions under NEC 2017 or newer. If you are installing a 14-50 for an EVSE, a GFCI breaker is required, while it isn't for other uses.

I mentioned this actually in previous post, just asking your local inspection department, they can probably answer your questions if it complies with local code (not every jurisdiction is on the same version, and there are plenty of local modifications).

 

[Lanzer]

Ok I want to bump this thread one more time and ask a question.... I know the 14-50 outlet is commonly sold adapter for the mobile connector and it's mainly because that is what is most widely used in the US in RV parks, campgrounds and such. I know most of the RV outlets are not 50 amp breakers. Usually 100amp breakers. So is it really that important to ONLY use a 50amp breaker???? I will install one and I've not even been using it as I've got by fine with 110 and supercharging on trips but just genuinely am curious and will install a 50amp breaker but I just can't see how it is that critical....

I'm not a EE but I am still baffled at the amount of responses suggesting you to install a 50amp breaker. It's like saying "you're using an iphone charger on your 20amp circuit? better change the breaker to a 1amp breaker!"

Whether you have a 100amp breaker or a 50 amp breaker isn't dependent on the outlet. It depends on what gauge wires are in that circuit. (of course, the wires and breakers are planned based off what outlets you plan to use) If the circuit has #3 copper wires, then you're fine. It might have 5 L6-20 outlets, or 2 14-50 connectors at the end, and if the total load is too high then the circuit will break before the wires get cooked. That's it.

In short, no one can actually tell you if it's safe to use that outlet based on the breaker itself. We don't even know if that outlet is the ONLY thing drawing from the circuit with the 100amp breaker, but more importantly, you haven't found out the actual wire gauge end to end. What you should do is:

- turn off the breaker
- make sure the outlet (you shown a NEMA 14-50 outlet in your photo) has no power (just plug your charger in to check)
- remove the screws securing the outlet to reveal the wires behind it
- you should see the wires leading to the outlet. On the wires there should be writing showing the wire gauge size. If you can't find the writing, grab a caliper for $5 and measure how wide the copper wires are.
(of course you can also open your breaker box, but not recommended unless you don't mind cutting power to the whole box)

Follow this chart to see if your breaker is suitable for the wire size you measure

Lastly, there are number of forums dedicated to contractors, with many certified electricians helping to answer questions. Anyone of them is 10X more qualified than hobbyists like me.

 

[T4M3]

I am an EE and I strongly suggest to install the correct wire size and a 50A breaker on the circuit that you have the 14-50 NEMA outlet installed since it is rated for 50A.

 

[Jeremy3292]

I'm not a EE but I am still baffled at the amount of responses suggesting you to install a 50amp breaker. It's like saying "you're using an iphone charger on your 20amp circuit? better change the breaker to a 1amp breaker!"

This is incorrect and your analogy doesn't make logical sense. The breaker will trip at anything past 20 amps, which is what the outlet (receptacle), breaker, and wiring is rated for. Plug in a 1 amp iPhone? No worries bc the entire circuit is rated for 20 amps and will shut off once you exceed 20 amps.

The breakers job is to prevent power surges or a fire when something goes wrong. It trips the breaker and cuts the power once you get past the breakers amp rating. If you have a 100 amp breaker, the power won't cut off and the breaker won't trip until 100+ amps. But in this example you have a 50 amp outlet and 50 amp wiring, so your entire circuit is NOT rated for anything past 50 amps. So any amp draw past 50 amps is a potentially dangerous situation as your breaker won't trip.

Whether you have a 100amp breaker or a 50 amp breaker isn't dependent on the outlet.

This is incorrect. The outlet is also rated for a certain amperage and volts. The outlet (receptacle), wiring, and breaker ALL must be sized together appropriately (aka the entire circuit).

I've created some examples below:

Receptacle - 50 amps
Wiring - 50 amps
Breaker - 50 amps
Verdict = GOOD

Receptacle - 50 amps
Wiring - 100 amps
Breaker - 50 amps
Verdict = GOOD

Receptacle - 50 amps
Wiring - 50 amps
Breaker - 100 amps
Verdict = BAD

Receptacle - 50 amps
Wiring - 40 amps
Breaker - 50 amps
Verdict = BAD

 

[SilverString]

Can anyone tell me what this is????




View attachment 816342

Nema 6-50 or 6-50R. Commonly used with RV's. 50A plug that needs 50 amp wiring (#6 minimum) and a 50 amp breaker. Maximum recommended continuous draw would be 40 amps or 80% of its rating. This would be fine for maxing out the the mobile charger at 32 amps, and if you were sizing the breaker for maximum safety protection you should use a 40 amp breaker, 80% of which is 32 amps. Using a 100 amp breaker makes no sense and increases the risk of fire from wiring and/or the melting of the 6-50 outlet. The 6-50 uses the neutral return (white) to provide 120v+120V+ ground for devices that use that config. No Tesla charger uses the neutral, only both hot sides + ground. The Tesla mobile adapter plug for this outlet does not connect the neutral to the plug prong thus creating the functional equivalent to the 14-50 for the charger.

 

[Jeremy3292]

Nema 6-50 or 6-50R. Commonly used with RV's.

It's a NEMA 14-50R...125/250 volts and has 4 wires. 6-50R has 3 wires and is rated for 250 volts only. See Tesla chart below:

 

[UncleCreepy]

I am an EE and I strongly suggest to install the correct wire size and a 50A breaker on the circuit that you have the 14-50 NEMA outlet installed since it is rated for 50A.

I, too, am an EE and I support T4M3's post. Apart from pulling the "I am an electrical engineer"-card: Isn't it common sense that an outlet rated for 50 Amps cannot be "protected" by a 100 Amp breaker? I don't think anyone needs a formal degree to understand this simple concept.

 

[SilverString]

It's a NEMA 14-50R...125/250 volts and has 4 wires. 6-50R has 3 wires and is rated for 250 volts only. See Tesla chart below:

View attachment 816445

Correct. I had the two types reversed.

 

[Lanzer]

I am an EE and I strongly suggest to install the correct wire size and a 50A breaker on the circuit that you have the 14-50 NEMA outlet installed since it is rated for 50A.

You're right, If for some reason the charger started pulling more than 50A or a short circuit, the receptacle can burn out before the breaker trips. I did not take into mind that the outlet is also part of the circuit, so the breaker gotta be designed for the lowest common denominator.

And that's why I'm just a hobbyist.

 

[3sr+buyer]

This is incorrect. The outlet is also rated for a certain amperage and volts. The outlet (receptacle), wiring, and breaker ALL must be sized together appropriately (aka the entire circuit).

I've created some examples below:

Receptacle - 50 amps
Wiring - 50 amps
Breaker - 50 amps
Verdict = GOOD

Receptacle - 50 amps
Wiring - 100 amps
Breaker - 50 amps
Verdict = GOOD

Receptacle - 50 amps
Wiring - 50 amps
Breaker - 100 amps
Verdict = BAD

Receptacle - 50 amps
Wiring - 40 amps
Breaker - 50 amps
Verdict = BAD

The easiest way to think about it is that the breaker must match the smallest amperage of the wiring or receptacle, so that all parts of the circuit are protected.

A setup that may be moderately common and allowed is:

Receptacle: 50A
Wiring: 40A
Breaker: 40A

This is allowed, because the breaker matches the smaller amperage (of the wiring). It may be done because there are no NEMA 14-40 or 6-40 receptacles or plugs. A 32A EVSE may be plugged into such an outlet.