Older homes without an equipment ground

[cppoly]

I'm sure this is probably been asked a hundred times but can someone help explain the hazards when an older home doesn't have an equipment ground and uses a three pronged receptacle.

For an appliance that has no grounding prong (2 prong only), there's no hazard right?

And if the appliance has 3 prongs, then there's a hazard?

 

[augie47]

An appliance with a 3 wire plug relies on the ground prong to route any leakage current to ground reducing the possibility of a shock hazard.
GFCI (breaker or receptacle) is a good alternative as it disconnects the circuit when minimal leakage is present.

 

[infinity]

For an appliance that has no grounding prong (2 prong only), there's no hazard right?

That's correct.

 

[Speedskater]

You will probably need small form factor GFCI dual receptacle to fit in those old small outlet boxes.

 

[Electromatic]

A receptacle with a ground hole that isn't actually connected to ground is not in itself a hazard. The objection is that it makes a user think there is a ground connection when there isn't. If a piece of equipment or appliance has a ground prong and also has a fault to ground, plugging it in to a grounded receptacle will (should) trip a breaker. If the receptacle isn't grounded, the fault could energize the frame or some other part of the equipment and create a shock hazard.
IMO, using the 2- to 3-prong cheater adapters is more of a hazard than an ungrounded 3-slot receptacle.* They make plugs stick out so much, they strain connections points, get jostled by furniture, passers-by, etc.
*(Except perhaps in the quite rare case where where the adapter is actually bonded through the plate screw, receptacle, box, wiring.)

 

[tortuga]

I have always been told 406.4(D) does not modify 250.114, so any equipment listed in 250.114 gets an equipment ground ran per 250.130(C).
For example in a old house with all ungrounded receptacles, I would use the GFCI replacement exception in places like bedrooms or living rooms, but equipment like window AC, fridge, clothes washer, dishwasher, dryer, sump pump, large computers etc gets an equipment ground ran to them. Often just as simple to run a new circuit to those appliances.

 

[newservice]

I have always been told 406.4(D) does not modify 250.114, so any equipment listed in 250.114 gets an equipment ground ran per 250.130(C).
For example in a old house with all ungrounded receptacles, I would use the GFCI replacement exception in places like bedrooms or living rooms, but equipment like window AC, fridge, clothes washer, dishwasher, dryer, sump pump, large computers etc gets an equipment ground ran to them. Often just as simple to run a new circuit to those appliances.

Sorry to disagree with whatever you were told, but I would simply replace 2 prong plugs in the bed and living rooms, and in the 250.114 locations that is where the GFCI protection or GEC would be mandatory. Large computers...or anything else for that matter are not supposed to rely on the GEC for operation or grounding of RFI, these are objectionable currents. Only fault current belongs in the GEC. For convenience I would put at least one 3 prong or GFI in every room like beds or dens etc. in my city this is in the property conservation electric code for older existing homes.
What’s key is to protect from a shock hazard so you just want to be aware of things like concrete floors even if carpeted, and grounded things like plumbing, radiators, etc. I would either use GFCI breakers or a GFCI receptacle. Of course you can daisychain the receptacles and use 3 prongs downstream from the GFItoo as long as you mark them no equipment ground and gfi protected with the little stickers ( which the electricity really won’t care if you affix them or not but an inspector might like to know.). However you have to be careful if the house has k&t because of the 3 wire branches utilizing the same neutral could end up tripping a GFCI if you daisychain them.

 

[tortuga]

Sorry to disagree with whatever you were told, but I would simply replace 2 prong plugs in the bed and living rooms, and in the 250.114 locations that is where the GFCI protection or GEC would be mandatory.

406.4(D) allows you to replace a receptacle with no equipment ground but 250.114 still limits what you can plug into it.

 

[Little Bill]

406.4(D) allows you to replace a receptacle with no equipment ground but 250.114 still limits what you can plug into it.

Which is one, if not #1, of the most unenforceable codes written!

 

[charlie b]

For an appliance that has no grounding prong (2 prong only), there's no hazard right?

I am going to (slightly) disagree with this and with Rob's having agreed to this.

Many years ago, manufacturers started offering tools with "double insulation." What that meant is that if a live wire contacted the case from the inside, the outside of the case (the part being held in the user's hand) would not become energized. Such tools were safe to use despite having a cord with a 2-prong plug.

However, any tool or appliance that has a metal exterior that is not adequately insulated from its interior can give the user an unpleasant shock, if a live wire contacts the case from inside.

So my answer to cppoly's question is, "sometimes, but not always."

 

[tortuga]

Which is one, if not #1, of the most unenforceable codes written!

Even if you see a clear dedicated area with other necessary hookups where one of the 250.114 appliances such as a sump pump, fridge or clothes washer clearly go and there is no grounded receptacles reachable without resorting to an extension cord?

But yeah depends on the AHJ and what their scope is, either way the liability is still there for the installer regardless if its enforced.

 

[Little Bill]

Even if you see a clear dedicated area with other necessary hookups where one of the 250.114 appliances such as a sump pump, fridge or clothes washer clearly go and there is no grounded receptacles reachable without resorting to an extension cord?

But yeah depends on the AHJ and what their scope is, either way the liability is still there for the installer regardless if its enforced.

Yet, the GFCI would make it much safer than just leaving the two prong receptacle in place!

 

[Little Bill]

Craziest thing is we are now required to put GFCI on things that have an EGC, with no apparent reason in some cases, such as stoves, car chargers that already have GFCI built in them, and dishwashers. But don't want us to put GFCI on 2-wre receptacles if something with a ground pin is going to be plugged in.

 

[newservice]

Well take the double insulated appliance with 2 wires. Sure, the frame is protected from an energized wire coming loose. However if you are standing in a puddle and you drop it in a bucket and fish it out, ZAP.
Double insulated didn’t help much there. For that matter a grounded tool or appliance wont help either . Maybe I’m being redundant if so apologies. So in a 2 wire home I still think you’re compliant with code if you just put GFIs in the locations specified elsewhere in this code

 

[electrofelon]

. However if you are standing in a puddle and you drop it in a bucket and fish it out, ZAP.

 

[Fred B]

For an appliance that has no grounding prong (2 prong only), there's no hazard right?

There is a UL requirement for portable tools and appliances that electrical components and motor be isolated (no contact with a conductive shell possible). So if compliant to that, not an issue. But use of a ground adapter to plug in a 3 to 2 prong receptacle puts user at risk of shock or electrocution thus the reasoning for requirement in the code when replacing a 2 prong (non-grounding) for a 3 prong (grounding) receptacle it be GFCI protected if no EGC present. Seen an appliance not a 240 volt but a gas range that had 240V to remote ground on an opened EGC and a shorted 2 circuit making contact to the EGC that didn't go back to panel. It also had 240V on a light switch strap, exhaust fan ducting, and J box enclosures.

 

[tortuga]

I still maintain that 406.4(D)(2) does not modify 250.114.
So in a dedicated area where one of the 250.114 appliances such as a sump pump, fridge or clothes washer clearly go (indicated by say plumbing hookups, individual circuit or whatever) and if there is only a non-grounding type receptacle to service an appliance being replaced 250.114 requires a equipment ground in order to plug in the appliance, and 406.4(D)(2) provides no relief from that.
406.4(D)(3) requires GFCI protection in places where the code currently requires GFCI's, so it would be a need to be a grounded GFCI receptacle at the fridge , clothes washer and or sump pump to be NEC compliant.
Its certainly better than nothing to at least have GFCI protection, but code compliance , enforcement, and 'better than nothing' are different things.

 

[Speedskater]

a] 'Double insulated' appliances have a Square within a Square safety symbol.

b] EGC primary task is to trip the breaker/fuse if the is a ground fault (short circuit to chassis)

c] GFCI primary task is to trip if there is any leakage current.