How to protect computer gear when power is ungrounded and dodgy?

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Elpie

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#151783 4-Sep-2014 20:56

This question is probably outside the experience of most NZ'ers but our imported geekzoners may be able to help me.
I'm moving to an apartment overseas that runs pretty much the whole place on one 15 amp circuit that is ungrounded and cannot be grounded. Brownouts are common and the lack of grounding concerns me. I will be running a UPS but surge protection is useless as surge protectors all require grounding.
What can I do to protect my gear?
Anyone have any ideas?

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3885 posts

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#1122188 4-Sep-2014 22:00

Run your gear via an isolating transformer. That way it will at least be able to block common mode surges. (Surge that appears on phase and neutral wire at the same time). And the inductance of the transformer will help to block fast rise time surges that appear on just the phase or neutral. And wire one of these across the output of the isolating transformer. And another one across the input. http://www.jaycar.co.nz/productView.asp?ID=RN3404&w=varistor&form=KEYWORD Also consider if there is anything that will "import" a ground into your apartment. Such as TV aerial, telephone / data cables, Intercom system, water pipes ect. As these sorts of things can also bring spikes or surges in as well. And you don't want to unintentionally be using your TV to ground all your electrical gear.

Inphinity

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#1122190 4-Sep-2014 22:04

I'd get a decent UPS.

Aredwood

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#1122222 4-Sep-2014 22:46

It would also help if you know or can find out what system of supply you will have in the building http://en.wikipedia.org/wiki/Earthing_system http://en.wikipedia.org/wiki/High-leg_delta

Elpie

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#1122245 5-Sep-2014 01:08

Inphinity: I'd get a decent UPS.

It's not a cure-all in this situation. A UPS running on dodgy power that is ungrounded is also susceptable to damage. I'm getting one, but its use is limited in this situation.

Elpie

1304 posts

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#1122246 5-Sep-2014 01:17

Aredwood: It would also help if you know or can find out what system of supply you will have in the building http://en.wikipedia.org/wiki/Earthing_system http://en.wikipedia.org/wiki/High-leg_delta

No idea. All I know of it is that it is old wiring in a building that is over a century old. In North America. Some three-point plugs were installed with the grounding wire cut off but most outlets have just the two-prong. The building is not earthed and the outlets not grounded.

shk292

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#1122298 5-Sep-2014 08:25

Motor-generator set? Used to be in wodespread use in naval ships but probably a bit big/noisy/expensive for domestic use on reflection

Aredwood

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#1122783 5-Sep-2014 21:49

Elpie:
Aredwood: It would also help if you know or can find out what system of supply you will have in the building http://en.wikipedia.org/wiki/Earthing_system http://en.wikipedia.org/wiki/High-leg_delta

No idea. All I know of it is that it is old wiring in a building that is over a century old. In North America. Some three-point plugs were installed with the grounding wire cut off but most outlets have just the two-prong. The building is not earthed and the outlets not grounded.

So the building will most likely be split phase. (Im guessing that by "North America" you mean either the USA or a country that follows the USA wiring rules) And also assuming that the outlets will therefore be 110V. Check what the max input voltage that your UPS can handle. As the worst case failure for the wiring in your building is a failed neutral. Which will cause the voltage at the outlets to double assuming almost no load on the phase you are connected to, and a large load on the other phase. But in reality there should be some loads on both phases, So the voltage increase (or decrease) in a failed neutral scenario will depend on how big the load imbalance is. Should also have added that the devices I linked to from Jaycar are surge protectors. (The actual component that does the surge protection). But you would probally want some with a lower clamping voltage as the Jaycar ones are intended for 240V mains.

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kiwigander

231 posts

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#1123409 6-Sep-2014 22:38

My accent and I hail from North America, I've got some familiarity with their electrical wiring, albeit on an amateur basis.

It sounds as if your building has the old "knob-and-tube" wiring used until, more or less, the 1930's. That predates the split-phase wiring of the last few decades. That is, it's likely the supply to the building is exclusively 110 or 120 V (no 220 - 240 V heating, water heating, dryer or electric range circuits).

The powerpoints are all two-blade without an earthing pin. If you could see the cabling you'd see separate phase and neutral cables running through porcelain knobs and tubes. I believe that neutral and earth are bonded only in the fusebox. You can Google knob-and-tube wiring for a more authoritative description.

So far, so bad, but the really scary bit is when someone has wanted to plug in an appliance that requires earthing and has replaced a powerpoint with a modern two-blade-plus-earthing-pin powerpoint <i>but the earth is not connected to anything</i>. That's something I discovered in an old house I was renting in the early 1980's where the only place I could plug in the electric lawn mower was one powerpoint in the kitchen. I checked that powerpoint and discovered the missing earth. (It's a long time ago, and I'm struggling to remember how I fixed it, but I remember running a cable from the earth conductor of that powerpoint down to the fusebox in the basement.)

At that time you could get "cheater" adapters that let you plug a two-blade-plus-earth plug into a two-blade-without-earth powerpoint. I earthed my computer (a Commodore PET) to the nearest cold water pipe with a length of cable from the earth lug of the cheater adapter. I don't think you want to try that.

You may luck out if your building was cabled with BX (armoured) cable. In that case the boxes into which the powerpoints are set should be earthed by the cable armour, and if you can find a cheater adapter and screw it onto the powerpoint, you may have a functional earth.

My suggestion would be to look for an online forum aimed at electricians in North America and ask there for advice.

Please do not take my comments as any kind of professional advice. The Americans especially seemed very casual about earthing for a long time and you could end up frying your computer or yourself.

Elpie

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#1123630 7-Sep-2014 14:35

Thanks kiwigander.

The place does, indeed, have the faked earthing-pin power outlets, allowing three-pin plugs to be used in the power point. The earthing has been cut off most of them, tied off on the rest. Most plugs are just the two blades and look like they could have been there since the turn of the 20th century. We paid for a master electrician to check out the wiring and had some repairs done (wiring where insulation had crumbled and fallen away and a dangerously-wired connection for the washer & dryer that was burning away in the wall). However, building regulations in Montreal say that as long as the wiring met code when it was installed it does not need to be changed. Like the US, Quebec does not require wiring to be done by professionals so anyone can do anything they like with it, basically.

It's kinda interesting to me to realise that we had made assumptions based on nothing in particular. I guess I expected the US and Canada to be more modern in their approach to things like wiring and plumbing. I certainly expected that in population-intensive urban areas safety would be regulated. And I expected that in countries with greater access to electronics that housing would be able to run such things.

To get there and find that having power outlets doesn't mean they can be used, or that you can't necessarily run computers, printers, or even TV's, and that gear requiring earthing is readily sold but actually having earthed wiring is unusual, has been a real eye-opener.

I've been on North American forums seeking tips & advice but thought to ask here as geekzoners tend to think creatively. The other places basically say we are sol and should find another place to rent (most of them are likely to have the same problems. Housing stock in Montreal is almost all over 100 years old) but we are locked into our lease for a year so have to find a way to protect our gear.

richms

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#1123733 7-Sep-2014 17:50

Earthing is overrated. If all the devices are running thru a single surge protector as well as any incoming coax etc, then all that matters to the appliances is the differences between the mains and the other signals, which the surge protector will clamp if there is a surge.

Earthing is a safety thing, for if your appliances develop a fault to the chassis. In which case a plug in RCD (or whatever they call them) will cut the supply in anycase.

Just make sure that _everything_ runs thru a single decent powerstrip surge protector and you have no other interconnections from that gear to other gear and you cant really do any more. There cant be a surge to ground if the equipement has no ground connection, its all floating. The lack of a proper ground is used as an out for the connected equipment insurance on powerstrips because it is an easy out for them.

Richard rich.ms

Elpie

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#1123772 7-Sep-2014 19:11

richms: Earthing is overrated. If all the devices are running thru a single surge protector as well as any incoming coax etc, then all that matters to the appliances is the differences between the mains and the other signals, which the surge protector will clamp if there is a surge.

Earthing is a safety thing, for if your appliances develop a fault to the chassis. In which case a plug in RCD (or whatever they call them) will cut the supply in anycase.

Just make sure that _everything_ runs thru a single decent powerstrip surge protector and you have no other interconnections from that gear to other gear and you cant really do any more. There cant be a surge to ground if the equipement has no ground connection, its all floating. The lack of a proper ground is used as an out for the connected equipment insurance on powerstrips because it is an easy out for them.

Don't surge protectors throw the surge to ground? Sorry if I sound ignorant (I am when it comes to power supplies ;) ) but reading up on surge protection has me (conned?) thinking that surge protection won't work without an earth/grounding. Without that, where do they throw the surge?

richms

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#1123777 7-Sep-2014 19:18

They throw a surge to ground when it is a surge that is above ground. That will only affect your gear if there is another connection to ground. The common mode protection is between the phase and neutral, which it will still protect against even with no ground connection.

Throwing surges onto the ground is often worse than letting both phase and neutral be effected equally, as suddenly there is a massive difference in voltage between your chassis of various pieces of gear that are interconnected. That is why all good surge protectors tell you to put all the connections thru them and exclude the connected equipment insurance if there are any other connections. The gear only cares about the difference between its chassis and the power wires. A surge protector will still clamp that. The only surges that get diverted to ground are lightning strikes and if one of those happens you are screwed anyway.

Richard rich.ms

DarthKermit

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#1123785 7-Sep-2014 19:47

I don't know, would an isolating transformer help in a case like this? And do they have them available in Canada?

Whatifthespacekeyhadneverbeeninvented?

kiwigander

231 posts

Master Geek

#1123788 7-Sep-2014 19:53

Bienvenue à Montréal, Elpie!

It was there that a sparkie repairing a ceiling batten in my 1920-era apartment tested the installation by sticking his finger into the socket and asking me to flip the switch on. It was live. (You can get away with that with 110 V but, judging by the expression on his face, it did hurt.)

At another apartment, the clips holding one of the mains fuses had perished. Another sparkie repaired this by bridging it with a piece of stout cable. He reckoned that the mains fuse on the other phase (this was split-phase wiring) would protect – whatever it was that was supposed to be protected.

I am not familiar with the code and regulations governing DIY electrical work in Québec (every province has its own regulations) but I know that in British Columbia, you could do anything, so long as you had each stage of the work (as defined by the provincial electrical inspector on your case) inspected.

AFAIK it is not considered necessary to remove knob-and-tube wiring, but you must not make new connections to it.

Anyway, I won't regale you with more stories from the Great White North.

Do all the surge protectors you can find have three pin plugs?

Perhaps you could try the cheater + earthing lead running to a cold water pipe? Or, if you're going to be there for a year, can you get an additional, properly earthed circuit installed? The service to the house should be at least 30 A – laughable in these days, I know, but I'm surprised that the entire house would be on a single 15 A circuit.

Sideface

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#1123790 7-Sep-2014 19:56

The place does, indeed, have the faked earthing-pin power outlets, allowing three-pin plugs to be used in the power point. The earthing has been cut off most of them, tied off on the rest. Most plugs are just the two blades and look like they could have been there since the turn of the 20th century. We paid for a master electrician to check out the wiring and had some repairs done (wiring where insulation had crumbled and fallen away and a dangerously-wired connection for the washer & dryer that was burning away in the wall). However, building regulations in Montreal say that as long as the wiring met code when it was installed it does not need to be changed. Like the US, Quebec does not require wiring to be done by professionals so anyone can do anything they like with it, basically. It's kinda interesting to me to realise that we had made assumptions based on nothing in particular. I guess I expected the US and Canada to be more modern in their approach to things like wiring and plumbing. I certainly expected that in population-intensive urban areas safety would be regulated. And I expected that in countries with greater access to electronics that housing would be able to run such things. To get there and find that having power outlets doesn't mean they can be used, or that you can't necessarily run computers, printers, or even TV's, and that gear requiring earthing is readily sold but actually having earthed wiring is unusual, has been a real eye-opener. I've been on North American forums seeking tips & advice but thought to ask here as geekzoners tend to think creatively. The other places basically say we are sol and should find another place to rent (most of them are likely to have the same problems. Housing stock in Montreal is almost all over 100 years old) but we are locked into our lease for a year so have to find a way to protect our gear.

(Legal) Third World wiring in a First World country.
I'm surprised.

Sideface

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