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I moved into a new rental house ~3 weeks ago. The house was built in 1950, and the house's dryer hook-up has a Nema 10-30P outlet (3 prong, see picture). Also, The kitchen electric range (supplied by property company, not mine) has a Nema 10-50 plug and receptacle, but no separate ground (not pictured due to bad lighting, sorry). My 4-ish year old dryer has a Nema 14-30 plug, so does not fit the 10-30 outlet. There is a separate ground wire hanging off the un-insulated ground wire coming from the circuit breaker next to w/d hook-ups. It looks shady, with zip ties holding wires in place. Everything I've read online says that Nema 10 outlets are no longer considered up to code (NEC 250.140), and the exceptions where you can hook them up safely with a separate ground wire come with very specific stipulations. My question is, are these two outlets, the 10-30P dryer outlet and the 10-50 range outlet, up to code and safe as they are, or should the property company be responsible for updating them to bring them up to code?

I mostly just want to be able to hook my dryer up safely. I know there are separate 10-30 plugs/cords for dryers you can buy at Home Depot, but I don't want to go that route if the true issue is an electrical code violation causing a safety hazard. The Property company has drug their feet for over 2 weeks about getting a maintenance person out to check the connections (which in my mind indicates that they know it's not up to code they were just hoping I wouldn't know/notice). If they are up to code and my research was wrong, I'll happy just pick up the cheap Nema 10 plug for my dryer and be on my merry way, but if this is truly a code violation and a fire hazard, then I want to stand my ground and insist the property company update the outlets.

Any advice or guidance is appreciated!

Edit: I'm sorry for the orientation of the pictures, they were taken on my phone.

Existing Dryer outlet in house Green ground wire for dryer (installed by someone prior to me renting home) is currently attached to other ground wire for house with zip ties Dryer outlet with separate green ground wire hanging from main ground, both of which run back up into main circuit breaker for the house

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    Welcome to StackExchange! Are you interested in "up to code", or are you interested in "safe"? Usually they are nearly the same, but not where NEMA 10 is concerned. – Harper Aug 21 '18 at 23:35
  • It appears that re-running the dryer branch circuit is an option -- is the same true for the range, or is there some other way you could get a #10 ground wire to it? – ThreePhaseEel Aug 21 '18 at 23:42
  • You don't even need to if the neutral is insulated or it's SE cable. In those cases you can retrofit ground, and the ground wire is right there waiting to be attached properly. – Harper Aug 22 '18 at 0:02
  • Harper - I'm interested in "safe", but I'm sure the property company is only interested in "up to code". If it would be safe to use this Nema 10-30 with my dryer if I hook up the ground cable, then that's doable. But if it's still a safety issue even with the separate ground, then I'll likely do some additional research and try to insist that the property company replace the outlet. – Katie Aug 22 '18 at 0:11
  • ThreePhaseEel - The range is ~30ft and two rooms away from the circuit breaker, and you'd have to either run it around the walls/doorways through the house itself or drill through two cinder block walls. I doubt the property company would allow me (or even an electrician) to do that latter, but I don't think the former is a workable solution. – Katie Aug 22 '18 at 0:15
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I'm going to focus on the dryer, both because it's your equipment, and because it's so very easy to fix. The panel is right there.

The problem with NEMA 10's "grandfathered" connection, while Code legal, is if anything goes wrong with the neutral wire, the equipment chassis energizes at 120V - touch it and you're dead. The NFPA's logic is "That hardly ever happens because these connectors are rarely disturbed". Yeah, right. It does happen, does kill people, and is often misreported as a miswired connection when it just had an ordinary failure. The rest of the electrical universe is designed so a simple wire break fails safe. Not NEMA 10! The appliance lobby won't let NFPA just put their foot down and mandate retrofits.

First, I am a renter. Heck will freeze over before I downgrade a NEMA 14 cord to a NEMA 10. (In dire straits, I might keep the NEMA 10 cord, remove the ground-neutral strap on the dryer (as if it were NEMA 14), and ground the dryer externally - my hunch is, in your case, that's what the last guy did. That green wire stinks like tenant work.)

Code legality

Most likely, the NEMA 10-30 receptacle proper is grandfathered, and as such, inherits being Code legal. Any modification of that circuit would void the grandfathering and require a modern 14-30 and /3 cable be installed.

The 3-wire cable from service panel to dryer receptacle lacks any proper tie-downs. It needs tie-downs. If it were me, I'd want it 6" longer and run it along the tan cable, but still, hose clamps are not proper tiedowns.

Other cables leaving that panel also seem to be improperly anchored to the wall.

Another code violation is lack of proper working space in front of the panel. There must be a 30"x30"x78" box in front of the panel for the electrician or homeowner to stand. It looks like water pipes intrude.

Of course these won't fix your dryer circuit.

Now look at the bare ground wire coming from the panel and going through the hole to parts unknown. That is most likely the Grounding Electrode System of the panel. We'll be gracious and presume this is fit and in good working order.

The green ground wire is an attempt at retrofitting ground. That is legal to do, in fact NEC 2014 greatly liberalized the rules for retrofitting grounds. Retrofit grounds can attach any of several places, and the Grounding Electrode system is one of them. That said, the green ground wire has 3 defects.

  • You can't twist it around and use a ty-wrap. The right thing there is a proper clamp, i.e. a small split-bolt.
  • The wire is not properly anchored to the wall. Leaving cables to go floppy-doppy is not legal. Retrofit grounds need to follow the same normal clampdown rules as any cable. Cinder block is a pain to work with, but I also see a lot of abandoned holes just waiting to be reused.
  • The green wire is much too long for any use I can imagine. It just seems to be wadded up, I suspect it used to ground the old dryer.

Ask the landlord to fix this and most likely they'll just remove the green wire. That would bring it to Code.

Now let's talk about how to get to Safe. Obviously being a tenant you need to ask the landlord to do this. I don't see where you can hold a gun to their head, so you may have to pay him. Keep in mind landlords can't do their own electrical, it's not allowed. But given the location of dryer receptacle and panel, this isn't even 30 minutes' work for an electrician.

1. Retrofit the ground

This only works if a) the existing cable has an insulated (white) neutral; or the existing cable is type SE.

You can change out the receptacle for 14-30, use the existing hot-hot-neutral, and then bring over that green ground wire to provide proper ground. This is allowed under the ground retrofit rules. The flaws in the green wire would need to be fixed obviously. Parts cost: $12.

Given that drilling into cinder block is a PITA, it'll help to get a receptacle that uses the same mounting hole pattern as the current receptacle. That type of receptacle is a matched set of cover+base, like this.

2. Run a new 10/3 cable back to the panel

Tear out the existing receptacle and cable back to the panel. Replace it with an entirely new 10/3 cable run. Put ground on the ground bar, neutral on the neutral bar, and hots on the existing breaker. Fit the NEMA 14-30 in any location you please (in cinder block, best to reuse existing holes). Parts cost: $20.

3. GFCI breaker

This answer is not Code but it is safe. This will arrest (not prevent) electrical shocks from touching the dryer. Then use a NEMA 10 cord, but don't attach the neutral-ground jumper. In this setup, the dryer is not grounded at all: as long as there aren't any ground faults in the dryer, the dryer frame is isolated. If there are ground faults and you touch the dryer and get zapped, then the GFCI will trip. Parts cost: $80 + the NEMA 10 dryer cord, just the thought of buying one of those makes me spit in my mouth.

4. Hail Mary: external ground.

This answer is also not Code because Code proscribes the NEMA 14-30 connector as the correct way to do this "but that would be modifying the house". In this case you fit the NEMA 10-30 cord, but again omit the neutral-ground jumper, leaving the dryer's chassis to float/be isolated. Then you reuse that green wire to ground the chassis. Fix the problems: the bad clamp, bad anchoring and excess length. Parts cost: $0 (not counting the NEMA 10 cord) and you could probably DIY this.

The oven/range

throws up hands I don't know what to do about that one. It's their socket and their equipment. You could leave it alone; pay them to retrofit a 6/3 cable ($$) and NEMA 14 socket and plug; or have the electrician install a GFCI breaker on the circuit. I'd probably do the latter as it's a 5 minute job.

  • Thank you for your detailed answer! This is very thorough and gives me the information I need to go to the property company. I now have a clear path forward. I agree I would like to use your option 1 to retrofit the ground to make the dryer safe to use if it's possible, even if I have to pay for the work myself. Thanks again! – Katie Aug 22 '18 at 16:40
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As you noted NEC 250.140 addresses how the metal frames of ranges and dryers should be grounded. The usual methods are hardwiring to an equipment ground wire (250.134) or a cord and receptacle with an equipment ground wire (250.138) but there is an exception for old three wire circuits without an equipment ground.

You can use a three wire cord and use the jumper inside your dryer or range to connect the frame to the neutral conductor if four conditions are met. It is important that the three wire cord connections are made correctly inside the appliance!

There is a diagram of the correct connection in an excellent answer to a similar question :)

wiring a oven with 4 wires to home service with 3 wires

Of the four conditions, the first is likely met - most residential services meet this requirement. The fourth only applies if you have receptacles on your appliances, and is likely met if the appliance is UL listed.

The second and third could be assumed OK if the receptacle was installed correctly, but you couldn't really know without having it checked.

Exception: For existing branch-circuit installations only where an equipment grounding conductor [ground] is not present in the outlet or junction box, the frames of electric ranges, wall-mounted ovens, counter-mounted cooking units, clothes dryers, and outlet or junction boxes that are part of the circuit for these appliances shall be permitted to be connected to the grounded circuit conductor [neutral] if all the following conditions are met.

(1) The supply circuit is 120/240-volt, single-phase, 3-wire; or 208Y/120-volt derived from a 3-phase, 4-wire, wye-connected system.

(2) The grounded conductor [neutral] is not smaller than 10 AWG copper or 8 AWG aluminum.

(3) The grounded conductor [neutral] is insulated, or the grounded conductor is uninsulated and part of a Type SE service entrance cable and the branch circuit originates at the service equipment.

(4) Grounding [ground] contacts of receptacles furnished as part of the equipment are bonded to the equipment.

  • Thank you! Yes, I am not an electrician so much of the language in those exemptions didn't really mean much to me. Upon checking the wire, it is AWG 8, and states it is CU Type MTW THWN, which I think makes it an SE cable? So it sounds like the dryer will be up to code and safe if I install properly. The range however, without a ground present at all, is not up to code. – Katie Aug 22 '18 at 0:19

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