Where is code on this one??

[zekeman]

Where is the protection on the 110v circuits in a range. Since the breaker is set at 50 amps, if I have a partial short(less than 50 amps) in the lighting circuit, I don't think there is sufficient protection. Please enlighten me.

Another issue which you have probably beaten to death- Is it a good idea to tie the neutral to the frame ground in a 3 wire system for an oven/range which takes 240V?

 

[Guest]

Re: Where is code on this one??

well grounding the neutral at the rangwe would be one way of testing the 50 amp breaker. Draw ot the circuit with the range as your load and I tjink you will answer your question.

 

[hbiss]

Re: Where is code on this one??

Where is the protection on the 110v circuits in a range?

I remember many years ago there used to be a 15A plug fuse under the cook top, at least in one major brand. I don't know how it's accomplished today, I'm not an appliance repair guy. However it's done rest assured it had to pass UL scrutiny since all appliances are UL listed so I wouldn't be concerned.

Is it a good idea to tie the neutral to the frame ground in a 3 wire system for an oven/range which takes 240V?

Hasn't been beaten to death because there is nothing to debate. Not only is it not a good idea it is against the NEC (as of, I believe the 1999 code cycle) for new installations and pertains to dryers as well. Never was legal if the circuit was being fed from a sub panel or the installation was in a mobil home.

-Hal

 

[electricman2]

Re: Where is code on this one??

Haven't purchased a new range lately. Do they come with the neutral/frame bond strap connected or not?

 

[jimwalker]

Re: Where is code on this one??

I believe most have no cord ,but the dealer will deliver it with the right cord.Won't ask who puts it on.The 3 wire idea dates back to world war 2 to save copper.The big question should be how to handle a range built back when they still offered a 110 receptacle(no gfci)

 

[zekeman]

Re: Where is code on this one??

Thank you for all your responses. However I'm still troubled by the fact that in the 3 wire system if, say you have a partial short- 3 ohm load in place of a light bulb you would get 40 amps in the 120V circuit.
Since the breaker is 50 amps then without a GFI in place, the breaker would hold and the 10 gauge wiring that is used for the lights would burn up.
I would think the neutral should have a separate 20 amp breaker.
What about this possibility??

 

[iwire]

Re: Where is code on this one??

A separate 20 amp breaker or fuse for the neutral would be a code violation. (240.22)

As for the other questions I agree with Hal (hbiss) UL has approved it, if what you are worried about was causing a problem recalls would be announced and UL would change any requirements necessary.

For all we know they may have a fusible link (a short section of small conductor) inside the range for the 120 volt loads.

the breaker would hold and the 10 gauge wiring that is used for the lights would burn up.

By the way 10 awg depending on the insulation is rated 30 to 40 amps, I doubt highly that 50 amps across a 10 awg would cause it to "burn up" before tripping a breaker or fuse, that is just my opinion no facts to back it up.

[ February 21, 2004, 09:12 AM: Message edited by: iwire ]

 

[websparky]

Re: Where is code on this one??

Please refer to:
250.140 Frames of Ranges and Clothes Dryers
for the neutral bonding.

Check 250.122, 10AWG is rated up to 60A for equipement grounding.

 

[charlie]

Re: Where is code on this one??

What is the type of insulation that is used? The older ranges use asbestos insulation so the wires will handle the loads, heat, and pass the UL tests. I really fail to see why you are that concerned with the internal appliance wiring unless you are working where you do not have the expertise to be. Sorta like a DIY.

 

[pierre]

Re: Where is code on this one??

If there is a ground fault or a short circuit in the 120v leg, it will open the OCPD. The problem that may occur with this is if it is an old installation with fuses, as it will only open the one fuse.
A lot of the new ranges and dryers are still shipped with the neutral post bonded to the frame.

An interesting situation I have seen lately is in kitchen remodels. The kitchen has a large portion remodeled and the range is located in the original location. The inspectors in our jurisdiction are requiring that the cable be reinstalled with 4 conductor if the existing cable does not have 4 conductors.

Pierre

 

[zekeman]

Re: Where is code on this one??

Charlie and others who have been so kind to respond:

The unit is a Jennair s125 circa 1986 which has no
asbestos insulation to my knowledge.

The reason I have brought up this subject is that I had a smoking short(breaker did not trip) in a switch which melted out 2 of its terminals (caused by spillage) that entered the cooktop and so I was wondering about the protection if any.

Since my post, I have located a circuit diagram which seems to confirm the lack of protection of the 110 circuit I described.

 

[pierre]

Re: Where is code on this one??

In this case the 'effective ground fault current path' may not be effective. If there is enough impedance in the path the result will most likely be no opening of the OCPD. Check the equipment grounding to the range to see if it is still intact or damaged.

Pierre

 

[hbiss]

Re: Where is code on this one??

...I had a smoking short(breaker did not trip) in a switch which melted out 2 of its terminals (caused by spillage)

The reason the breaker didn't trip was because this wasn't a "short" or ground fault, but rather increased series resistance of the switch contacts. The contacts of the switch overheated because of the contamination, probably began arcing, and the case of the switch and the insulation on the wiring leading to it began to burn. The rest is history. Happens all the time with circuit breakers where the lug screw isn't tightened properly.

I also don't see what this has to do with a 110V circuit unless this switch was for a light or maybe a blower?

In any case the outcome would be the same, the OCPD will not trip because there is no increase in current. This is precisely the reason that AFCI breakers were invented.

-Hal

 

[a.wayne3@verizon.net]

Re: Where is code on this one??

If you look inside the ranges today they still have 3 terminals 2 hot and a ground.Still have to be 4 wire from panel to receptacle and have a 4 wire cord and cap.

 

[hillbilly]

Re: Where is code on this one??

The new ranges have the grounded and grounding (white and green) conductors bonded to the frame as shipped from the factory. To be code compliant on a NEW installation you must isolate the grounded (white) conductor and leave the grounding(green) bonded to the frame, No?... This requires a 4 conductor cable on new circuits. Read 250-134., 250-138., 250-140. and 250-142.(b)
steve

 

[hbiss]

Re: Where is code on this one??

Hillbilly is correct. The reason the neutral and ground are bonded from the factory is because when it is used with an old 3 wire branch circuit the installer would have to remember to bond the two. You know this isn't going to happen in a lot of cases leaving the frame ungrounded. With the factory jumper, if the installer does nothing at least the frame is grounded regardless if the branch circuit is 3 wire or 4 wire.

-Hal

 

[jimwalker]

Re: Where is code on this one??

Anyone come across them cook top with only 2 hots and grounds.No neutral needed.Inspector on one house forced us to add a neutral that went no where so we could meet the 4 wire code .Now there was a real smart inspector

[ February 23, 2004, 06:38 PM: Message edited by: jimwalker ]

 

[racraft]

Re: Where is code on this one??

Just because the current cooktop doesn;t need a neutral doesn't mean that the next cooktop won't.

Many homeowners (and yes, some electricians also) would simply install a replacement cooktop and make it work with the three wire connection, even though by design and by code it would need a return.

 

[jimwalker]

Re: Where is code on this one??

We ran 10-3 w g to junction box.The top had a pigtail with no neutral.So we added a neutral and wire nuted it off in cooktop.