Stupid Question?

[chevelle64]

I am updating wiring in an old travel trailer. I'm running 12 ga wire from a 20 amp breaker to feed an electrical outlet. I will be feeding a single light fixture from the back of the outlet. The fixture would normally require 14 ga wire. Can I use 14 ga wire from the outlet, being fed by 12 ga wire, to feed the light fixture? Or is it the whole path of least resistance thing? Hopefully that wasn't too stupid. Thanks in advance.

 

[ghnl]

Protect the circuit for the weakest 'link' in the chain. For example, 14ga is usually rated for 15 amps, 12 ga for 20 amps. So, although you have some 12 ga wire in the circuit, the 14 ga would mean use a 15 amp fuse/circuit breaker.

 

[marty_p]

RE:

Right on advice: always protect the weakest link!!!

 

[sberry]

In most cases code calls for any part of the circuit to be 12 but for a single fixture I wouldn't lose sleep with a 14 wire feeding it as long as it couldnt be added on to, such as another recept in the future. Most fixture wiring is even lighter, usually 16.
Not that it was right but I recently took apart a circuit in a house where the switch loop to the overhead fixture was 16 lamp cord, was like that for 50 yrs. The guy that did it probably figured the load was limited due to the single fixture. Want to follow the letter use a 12.

 

[chevelle64]

Thanks for the replies guys. That's kinda what I was figuring, but I wanted to make sure. No sense in taking a chance with something like that. Fire is bad!

 

[BioHazard]

Hmmmm....I don't think code really applies in a travel trailer, does it?

 

[Norcal]

Hmmmm....I don't think code really applies in a travel trailer, does it?

See article 551 so in answer to your question, yes.

 

[sberry]

Yes, but, one of the reasons I just mentioned that I might not lose sleep over the 14 is 551.43 B,

but I wanted to make sure. No sense in taking a chance with something like that. Fire is bad!

I am a big believer in code, this does fall under the common sense code though to some extent too is why I mentioned it in the first place. There just isn't real concern of fire danger from feeding a fixture with 14. Its one of those things that if they allowed it pretty soon you would find 14 all over with people putting taps on it without considering the whole concept. There are places it is allowed on machines, etc with control wiring, they just know someone isn't going to come along at future time and add a couple duplexes on it.

 

[Mickey O]

From the 2008 NEC.

Exception No. 1: Where the assembly, including the overcurrent devices protecting the branch circuit(s), is listed for operation at 100 percent of its rating, the allowable ampacity of the branch circuit conductors shall be permitted to be not less than the sum of the continuous load plus the noncontinuous load.

Exception No. 1: Conductors tapped from a 50-ampere branch circuit supplying electric ranges, wall-mounted electric ovens, and counter-mounted electric cooking units
shall have an ampacity of not less than 20 amperes and shall be suffıcient for the load to be served. These tap conductors include any conductors that are a part of the leads
supplied with the appliance that are smaller than the branch-circuit conductors. The taps shall not be longer than necessary for servicing the appliance.

(4) Other Loads. Branch-circuit conductors that supply
loads other than those specified in 210.2 and other than
cooking appliances as covered in 210.19(A)(3) shall have
an ampacity sufficient for the loads served and shall not be
smaller than 14 AWG.
Exception No. 1: Tap conductors shall have an ampacity
suffıcient for the load served. In addition, they shall have an
ampacity of not less than 15 for circuits rated less than 40
amperes and not less than 20 for circuits rated at 40 or 50
amperes and only where these tap conductors supply any of
the following loads:
(a) Individual lampholders or luminaires with taps extending
not longer than 450 mm (18 in.) beyond any portion
of the lampholder or luminaire.
(b) A luminaire having tap conductors as provided in
410.117.
(c) Individual outlets, other than receptacle outlets,
with taps not over 450 mm (18 in.) long.
(d) Infrared lamp industrial heating appliances.
(e) Nonheating leads of deicing and snow-melting
cables and mats.
Exception No. 2: Fixture wires and flexible cords shall be
permitted to be smaller than 14 AWG as permitted by
240.5.

 

[sberry]

As was noted there is a section that pertains specifically to travel trailers, as 551.3 says,,,,,,,,,,,

 

[Mickey O]

The NEC does have a section for RV's and vehicles but unless it has been adopted by the Feds or the AHJ it doesn't mean ****.

 

[sberry]

So, one part of the code applies but the other does not?

 

[Mickey O]

So, one part of the code applies but the other does not?

No, I think the NEC has been adopted by the Fed for those mobile homes people live in but not for travel trailers. I just posted that part of the NEC to illustrate that they allow the tapping of circuit with a lower ampacity rated wire. Some seem to be under the impression that what he's proposing is very unsafe, it's not and is commonly done on kitchen circuits.

 

[sberry]

The code is specific to travel trailers, this part of it does not include mobile homes, a different part of it covers those. Travel trailers are sold in many states, no local inspections each time a trailer is delivered. The purchaser depends on the fact it meets NEC, and I would assume it must meet the latest version at the time of mfg.

 

[Mickey O]

The code is specific to travel trailers, this part of it does not include mobile homes, a different part of it covers those. Travel trailers are sold in many states, no local inspections each time a trailer is delivered. The purchaser depends on the fact it meets NEC, and I would assume it must meet the latest version at the time of mfg.

I have no idea but I can tell you there are parts of Illinois that have no electric code at all and that I could do what ever I want, if I want to run 14 ga wire on 30 amp circuits I could do it and wouldn't be violating any law. I suppose if the trailers are built somewhere where the NEC has been adopted and the trailer section applies they would have to follow the code. The NEC is not the law of the land, for it to apply it has to be adopted. So if I had a travel trailer and brought it to a place that hasn't adopted the NEC and doesn't have a travel trailer law I could wire it any way I choose.

The point I was making is that tapping a 14 ga wire off a 12 ga wire on a 20 amp circuit for a light that is pulling way less than 15 amps is not dangerous and is quite acceptable as illustrated in one of the exceptions above from the NEC.

 

[sberry]

The point I was making is that tapping a 14 ga wire off a 12 ga wire on a 20 amp circuit for a light that is pulling way less than 15 amps is not dangerous and is quite acceptable as illustrated in one of the exceptions above from the NEC.

You are correct in the assumption that it is safe but its not from that particular code section.
I can only assume and this involves some speculation about the original post that the guy is restoring this trailer and found this condition and wonders if this is really ok or if its a hazard. It basically follows the fundamental principal that the wire is suited for the connected load and is adequate to provide short circuit protection, which it is provided the ocpd is 20A, other parts of the code dealing with appliances allow it to 40A but its not part of the building wiring, its internal.

 

[sberry]

I have no idea but I can tell you there are parts of Illinois that have no electric code at all and that I could do what ever I want, if I want to run 14 ga wire on 30 amp circuits I could do it and wouldn't be violating any law.

Here is my take on that and some lawyers could likely clarify it. While there may be someplace that hasn't adopted code it wouldn't exempt one from negligence, especially knowingly violating standard work practice.
We have a case in court near here now where a woman had faulty exhaust on her car, gassed her kids. A lawyer might be able to argue that she hadn't violated a law but we will see.

 

[sberry]

I disagree with the OP on the thread title, I don't think it was a stupid question.

 

[Mickey O]

Here is my take on that and some lawyers could likely clarify it. While there may be someplace that hasn't adopted code it wouldn't exempt one from negligence, especially knowingly violating standard work practice.
We have a case in court near here now where a woman had faulty exhaust on her car, gassed her kids. A lawyer might be able to argue that she hadn't violated a law but we will see.

I understand that and would never do anything I though was dangerous, but not so long ago I was working in a part of Illinois that has no electrical code. I was talking to one of the county guys and I jokingly said to him "I could wire the whole house with extension cords", I was expecting him to say no or look shocked but he said, "sure could".

 

[Mickey O]

You are correct in the assumption that it is safe but its not from that particular code section.
I can only assume and this involves some speculation about the original post that the guy is restoring this trailer and found this condition and wonders if this is really ok or if its a hazard. It basically follows the fundamental principal that the wire is suited for the connected load and is adequate to provide short circuit protection, which it is provided the ocpd is 20A, other parts of the code dealing with appliances allow it to 40A but its not part of the building wiring, its internal.

No not internal, you can pull a line off an appliance circuit up to a vent hood if you want.

 

[sberry]

I can tell you are concentious and not a slob. You are right, the guy cant enforce anything as a code hasnt been adopted which is basically a contract and a waiver allowing 3rd party jurisdiction. Very similar to a drivers license or even a common tax return. Same for a permit, allows the govt to come in and inspect, as soon as you apply for it you agree to the terms.

No not internal, you can pull a line off an appliance circuit up to a vent hood if you want.

I would be glad to read that, where is it located?

 

[Mickey O]

Exception No. 1: Conductors tapped from a 50-ampere branch circuit supplying electric ranges, wall-mounted electric ovens, and counter-mounted electric cooking units shall have an ampacity of not less than 20 amperes and shall be suffıcient for the load to be served. These tap conductors include any conductors that are a part of the leads supplied with the appliance that are smaller than the branch-circuit conductors. The taps shall not be longer than necessary for servicing the appliance.

(4) Other Loads. Branch-circuit conductors that supply
loads other than those specified in 210.2 and other than
cooking appliances as covered in 210.19(A)(3) shall have
an ampacity sufficient for the loads served and shall not be
smaller than 14 AWG.
Exception No. 1: Tap conductors shall have an ampacity
suffıcient for the load served. In addition, they shall have an
ampacity of not less than 15 for circuits rated less than 40
amperes and not less than 20 for circuits rated at 40 or 50
amperes and only where these tap conductors supply any of
the following loads:
(a) Individual lampholders or luminaires with taps extending
not longer than 450 mm (18 in.) beyond any portion
of the lampholder or luminaire.
(b) A luminaire having tap conductors as provided in
410.117.
(c) Individual outlets, other than receptacle outlets,
with taps not over 450 mm (18 in.) long.
(d) Infrared lamp industrial heating appliances.
(e) Nonheating leads of deicing and snow-melting
cables and mats.
Exception No. 2: Fixture wires and flexible cords shall be
permitted to be smaller than 14 AWG as permitted by
240.5.

 

[sberry]

Where does this include vent?

 

[Mickey O]

Where does this include vent?

It doesn't specifically say vent, but it doesn't prohibit a vent, as long as it's not specifically prohibited it's fine.

 

[BioHazard]

This is basically the same thing as plugging in a standard reading lamp into a 20A wall socket. The lamp will probably have an 18 gauge cord, and that's perfectly safe, since the only thing it could EVER power is the bulb.

 

[sberry]

It specifically lists the equipment that its applicable, cook tops and ovens. A while back I replaced an oven in my folks home, it was wired by a legit sparkie back in the day. Not much has fundamentally changed about this part of the code except grounding and while I was at it I changed out some wires for dryer also, all to 4 wire. The oven and cook top were separate units all wired to a 50A circuit, the old oven had 3 K or so load as did the new one. Since it was hooked to this 50A they had 12 wire, code compliant and the guy new, he was thrifty with wire, range hood was separate and not connected to the unit, wired to a separate circuit. If it would have been legal to connect it he would have. He knew the letter of the code. I did run separate circuits to oven and cook top, since I did I could go to 14 wire as it was on its own breaker now, would have had to use 12 if I reconnect to same feed as the original.
There are places they do allow this type of wiring but they are very specific, if they list what is allowed it excludes things not listed. Code language is funny that way.

 

[hidollartoys]

In regard to Mickey O's post #9..... The "Tap" in question is not a branch circuit as defined by NEC. So the article sections might not be entirely pertinent. Additionally I am not sure that this "tap" is in the spirit of the code by definitation. If so then 240.21(2005 code) should come into play and wire guage is dependent on the OCPD and is defined by "tap" length.

Just my take.

 

[sberry]

This is basically the same thing as plugging in a standard reading lamp into a 20A wall socket. The lamp will probably have an 18 gauge cord, and that's perfectly safe, since the only thing it could EVER power is the bulb.

I want to add a bit to this. Its not always the same as using the 18 on a 20A, the unit in question may have internal wires smaller than the 14, designed to be limited to a 20, if its installed on larger circuits we may have something with internal wires too small for adequate short circuit protection.

 

[sberry]

As an example is the cook top that has 14 wire in and limited to a 40A breaker, yes the load is calculated so it doesn't over heat the wire but all the internal wire is rated for shorts up to 40. The vent hood may have wire as low as 18 in it.

 

[chevelle64]

Thanks for the help guys. Camper is progressing nicely.