noob - Power supply, home wiring and safety

[eco_bach]

Building a 3GPU (3XTitan Xp's) for rendering. Based on initial research I guestimate almost 1000W under maximum load when rendering.

Since I'm a total noob when it comes to things electrical and also because I live in an older building(no fuses, just circuit breakers) I thought it best to ask for feedback on safety.

Does 1000W sustained over long intervals (8-24hrs) pose any risk to typical, or even older home wiring?
I checked the circuit breaker box and can only see a rating of 100amp at the top of the box, nothing listed for individual switches.

 

[ss202sl]

Not an electrician, and even if I was, I wouldn't answer that question without inspecting your electrical system.

 

[SchizTech]

Well, starting from basic electrical theory: Power (in watts) = potential difference, or voltage (Volts) x current, symbolized I (measured in Amps), so flipping around to solve for amps, I=P/V.

On a 120V power line (give or take a few volts in real life), 1000W/120V= 8.3 amps. That's a long way from breaking that circuit breaker. Put another way, a common microwave or even hair dryer uses quite a lot of power. Circuits that have no problems with devices like that won't care if it's a PC using the watts.

 

[photonboy]

I want to ask some performance questions first:
1)First, are you absolutely certain you will BENEFIT from those graphics cards?

For the EXACT SOFTWARE you intend to use.

2) How would that compare to 2xGTX1080Ti for example (one less card and less VRAM per GPU)?

3) Or what about a QUADRO card of the same budget? Again, you must look at the EXACT same software.


POWER:
You would only damage the power cables if they were insufficient for the power breaker. The point of the breaker is to trip the circuit and prevent too much power drawing.

Amperage = Watts / Voltage

= 1000W / 12Volts
= 83Amps

It's possible you'll trip the circuit breaker when other devices are also turned on, especially if there's a temporary spike in the power draw of the PC.

What about a kitchen STOVE or Microwave? Those can use a lot of power too.

Without knowing the EXACT layout of the wiring I think tripping the circuit breaker is a concern. I don't think DAMAGE is a concern as it should simply trip the circuit breaker rather than overheat the wiring (which would generally just cause a fire, not long-term damage).

 

[photonboy]

Well, starting from basic electrical theory: Power (in watts) = potential difference, or voltage (Volts) x current, symbolized I (measured in Amps), so flipping around to solve for amps, I=P/V.

On a 120V power line (give or take a few volts in real life), 1000W/120V= 8.3 amps. That's a long way from breaking that circuit breaker. Put another way, a common microwave or even hair dryer uses quite a lot of power. Circuits that have no problems with devices like that won't care if it's a PC using the watts.

Correction, my math was wrong.

It was closer to 8Amps as said.

 

[MrN1ce9uy]

The power supply will draw more power from the wall than it delivers to the system. It depends on the power supplies efficiency as to how much power is lost in the conversion process. 90% efficiency on a system using 1000W to components is drawing ~1110W from the wall.

 

[SchizTech]

Well, starting from basic electrical theory: Power (in watts) = potential difference, or voltage (Volts) x current, symbolized I (measured in Amps), so flipping around to solve for amps, I=P/V.

On a 120V power line (give or take a few volts in real life), 1000W/120V= 8.3 amps. That's a long way from breaking that circuit breaker. Put another way, a common microwave or even hair dryer uses quite a lot of power. Circuits that have no problems with devices like that won't care if it's a PC using the watts.

Your math is wrong.
The graphics cards and CPU are using 12V power from the PSU. If the PSU is delivering 1000W that's 83Amps being drawn from the power supply, and thus possibly 1200W from the wall.

(not sure if that 1000W is supposed to be wall power or power from PSU, but if it's from PSU then it's almost 100Amps assuming about 85% PSU efficiency since the PSU dissipates the other power as heat)

Also, that 120V is AC, not DC.

That would be 83A inside the system. Voltage on a line is constant though (when not transformed via an AC transformer). If the PC were drawing 83A on the wall socket, that would be close to 10,000W. In lowering the voltage from outside to inside by a factor of 10, the PSU must also change the current by the inverse ratio.

MrN1ce9uy has a point about efficiency though.

 

[MrN1ce9uy]

It depends on the gauge of wiring going from the circuit breaker to the wall outlet as to how much it can handle. If the house was wired correctly, the wiring would be sufficient for the breaker to trip before too much power went through the lines and burned the lines up. A common breaker is 20A*110V=2200W on that single breaker before it tripped. You could go look at your breaker box and see what the Amperage is on the breaker that you will be using.

There are other variables to consider though. Was the house wired properly? Are there any open wires from poor installation? Could mice have eaten through the protective coating on the wire? There are things that could still present a danger. I'm not an electrician, but I did do some mining and had to think about these things.

 

[photonboy]

*YES. I WAS WRONG. I CORRECTED MY POST TOO LATE*

To confirm I checked a 1200W Microwave (120Vac) and it's rated for 12.7Amps.

It would be very difficult to draw 100Amps in most apartments or small houses at one time.