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-   -   Connecting ground to neutral in old 120v 2-prong outlet (http://www.diychatroom.com/f18/connecting-ground-neutral-old-120v-2-prong-outlet-85824/)

flow 11-04-2010 10:17 PM

Connecting ground to neutral in old 120v 2-prong outlet
 
I just recently moved into a room in a house build in 1947. The landlady doesn't know the exact history of the wiring in the house but the outlets in my room and the living room all have just two wires running to them (even though some had 3-pronged outlets...grrr) and so I am assuming are not grounded. I want to plug my computer in but would like to plug in a surge protector as well.

I am wondering if (and I will get an electrician to check) the two wires are the old kind and one is hot (120v) and the other neutral (instead of two wires caring 120v and a ground), could I connect the neutral wire to both the neutral terminal and ground terminal in a 3 pronged outlet to ground it (since neutral runs to ground) and get a surge protector to work?

I know this stuff can be tricky and dangerous so I'll probably have an electrician have a look at it either way, but I would like to understand as much as possible about any available solutions since the landlady is not interested in rewiring the house to have it grounded.

Any tips and suggestions are greatly appreciated.

Thanks

Jupe Blue 11-04-2010 10:27 PM

No, you may not jumper the neutral to the ground screw. It's a code violation. The code allows you to replace an ungrounded (2 wire) receptacle with a GFCI. This solution will not provide an equipment ground.

If you need a receptacle with an equipment ground you will have to re-wire the receptacle with a cable that has a hot, neutral and ground wire.

Get your landlord to pay an electrician to wire a grounded receptacle (either from an exisiting grounded circuit or a new circuit) near where you want to have your computer. As a tenant, you should not be working on the electrical system anyway. That's the landlords responsibility.

McSteve 11-04-2010 10:30 PM

Do not connect ground to neutral! This is wrong, illegal, dangerous, bad, etc.

This is called a bootleg ground. It almost killed me once where someone had done this and also managed to reverse polarity, thus putting 120v on the cover screw, and the chassis of the computer plugged in to the outlet.

Get an electrician. He'll probably recommend replacing the 2-prong outlets with GFCI-protected outlets, which still doesn't give you a ground for your surge protector, but is still much safer than having to use those "cheater" adapter to plug in 3-prong cords.

Scuba_Dave 11-04-2010 10:41 PM

Also buy a UPS to protect your PC
Instead of the power strip

flow 11-04-2010 10:48 PM

ok thanks guys,

I certainly don't want to put any future tenants or electricians in harms way.

I'll hire an electrician and hopefully he can find a ground for the outlet and hopefully the landlady will be willing to pay for it if it's a possible solution. Otherwise I guess I'll ask him to install a gfi outlet and just plug my old laptop into it until the lease is over and I can find a new place... sigh if only I had noticed the 2-pronged outlets before moving in, I guess now I'll know to check in the future!

Thanks again

flow 11-04-2010 10:54 PM

scuba_dave,

will a ups do much without a grounded outlet though? even if it is one with surge suppression capabilities I don't think it will be able to divert surges without a grounded outlet. Correct me if I'm wrong but I think all it would do is just keep the equipment running if the power goes out, not divert any surges.
I'm really more worried about damage to my hardware from surges than loosing files and software, I back everything up anyways.

McSteve 11-04-2010 11:19 PM

A good on-line UPS will protect your equipment 99% of the time. They essentially power your computer from the battery all the time, while keeping the battery charged with the incoming power. This way your computer gets clean conditioned power even in the face of most surges and sags. In the event of a lightning strike to your building or nearby utility pole though, all bets are off. Lightning can do funny things.

flow 11-04-2010 11:38 PM

Mc_steve, thanks for the reply. I read up on ups's a little more and it sounds like they protect your hardware against surges but spikes can only be diverted by a surge protector, right? So in your opinion would it be safe enough to run my desktop with a ups plugged into an ungrounded outlet? Aren't there other things besides lightning that could cause spikes though, or are they uncommon enough that it would be ok?

The place I moved into is a six month lease and if I really need to I can hold out and not use my desktop for that period of time and use the computers at school to get access to the software I need. I have an old laptop that I would be less worried about damaging that I could use for email, music, etc...

kbsparky 11-04-2010 11:45 PM

Many surge protectors don't work properly on non-grounding circuits. There is nothing to divert the surges to.

While using a GFI device on a non-grounded circuit can protect personnel, it won't do anything to protect your equipment.

Better to install a properly wired and grounded outlet for your sensitive computer equipment, etc.

AllanJ 11-05-2010 05:33 AM

Take a long bare wire (14 or so gauge) and daisy chain it from the chassis of one piece of equipment to the next. Connect the far end to a known ground such as a radiator in a water or steam heating system or better yet the ground lug or terminal strip or ground bus in the panel (run thje wire up and around doorways in the case of the latter).

A metal water pipe in the nearest bathroom might not be a good ground since there might be plastic pipe between it and the basement.

Alternative way of connecting the ground wire to the equipment: Use ordinary modern power strips and surge protectors and plug the final power cord into a 3 to 2 prong adapter and then into the receptacle. Connect the bare ground wire mentioned above to the ground lug on the adapter. You may use the screw that holds the outlet cover plate on to assist in holding the equipment end of the bare wire to the adapter.

Jim Port 11-05-2010 09:41 AM

Quote:

Originally Posted by AllanJ (Post 528900)
Take a long bare wire (14 or so gauge) and daisy chain it from the chassis of one piece of equipment to the next. Connect the far end to a known ground such as a radiator in a water or steam heating system

Absolutely against code.

Quote:

Originally Posted by AllanJ (Post 528900)
A metal water pipe in the nearest bathroom might not be a good ground since there might be plastic pipe between it and the basement.

Again not a compliant means of grounding.

Quote:

Originally Posted by AllanJ (Post 528900)
Alternative way of connecting the ground wire to the equipment: Use ordinary modern power strips and surge protectors and plug the final power cord into a 3 to 2 prong adapter and then into the receptacle. Connect the bare ground wire mentioned above to the ground lug on the adapter. You may use the screw that holds the outlet cover plate on to assist in holding the equipment end of the bare wire to the adapter.

If the box and cover plate are not grounded this does absolutely nothing.

Please try to review the valid options to retrofit a non-grounded receptacle and circuit.

AllanJ 11-05-2010 05:39 PM

Quote:

Originally Posted by Jim Port (Post 528994)
Absolutely against code.

Please try to review the valid options to retrofit a non-grounded receptacle and circuit.

I am not retrofitting receptacles here.

However a receptacle box may be retrofitted by substituting a 3 prong receptacle and running a ground wire of the same gauge (12 or 14) from it to the panel, more or less following the route of the existing wiring and leaving the existing wiring intact.

downunder 11-05-2010 08:28 PM

Quote:

I am not retrofitting receptacles here.
No sir! Sounds like something else to me.

emolatur 11-07-2010 11:26 PM

:D I frequently make reference to the fact that the electrical code cannot possibly dream of being enforced against the end users. Put another way, the AHJ is never going to stop by and inspect each and every lamp you've chosen to plug in.

I don't like the idea of grounding to "random stuff" either (radiators, etc.), but it's hard to define it as 'illegal'. I definitely can't do it as an electrician, but if someone who moves into a house I've wired chooses to do this, there's really nobody to tell him he can't, so long as it doesn't constitute a permanent installation.



NOW, about those surge suppressors and the lack of grounds...

Surges are moments of increased voltage. Voltage can only exist across two points. A surge, relative to ground, only matters if there is a ground.

If there isn't a ground, you can't clamp line-ground surges. However, nobody cares, because you can't HAVE line-ground surges without a ground. It would be a line-to-nothing surge, and "nothing" does not constitute a valid point to measure voltage to. Your computer will never see the surges, because your computer won't be grounded.

Grounding your computer (and surge suppressors) is more about RFI shielding (and to some extent shock prevention in case something goes wrong inside the PSU) than surge suppression.

My computers aren't grounded right now. I'm probably stopping my neighbors from receiving a couple distant radio stations, and if the SMPS chooses to go psychotic and short hot-to-case, I'm going to get lit up trying to change a CD, but I'm not worried about power surges damaging the electronics.

McSteve 11-08-2010 07:51 AM

Regarding the idea that you can't have a surge if you don't have a ground, I have to respectfully disagree. If you can have voltage at all, why can't you have higher-than-normal voltage?

As a dramatic example, what if tree branch snaps a primary phase between utility poles and drops it onto a secondary phase? Suddenly you've got maybe 7,200 volts to deal with between hot and neutral. :eek: It may only last a few cycles before it burns clear, blows a fuse, or opens a recloser, but that's more than enough to wreck your day.

I believe that decent surge protectors may have a MOV between hot and neutral, which will essentially shunt the current to neutral, thus clamping off the surge before it can damage connected equipment. The surge protector probably would not survive this.

Surge protectors that only have MOVs between hot & ground and maybe neutral & ground would do nothing in this instance, without an equipment ground present.


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