Protection for electronic devices

[electro7]

Hi,
I will be working on an old house that only has two prong outlets installed. As far as I know there is no equipment grounding conductor run to the outlet because of that (I have not opened it up yet). From what I understand, if I put a GFCI at the beginning of the circuit it will protect the equipment being served. Is this correct? And will the GFCI protect them from all fault current including ground fault? And will this protect a flat screen tv or a computer?
Would it be even better to add a surge protector as well? What exactly does a surge protector do? Protect electronic equipment from lightning?
Thanks!

 

[Little Bill]

Hi,
I will be working on an old house that only has two prong outlets installed. As far as I know there is no equipment grounding conductor run to the outlet because of that (I have not opened it up yet). From what I understand, if I put a GFCI at the beginning of the circuit it will protect the equipment being served. Is this correct? And will the GFCI protect them from all fault current including ground fault? And will this protect a flat screen tv or a computer?
Would it be even better to add a surge protector as well? What exactly does a surge protector do? Protect electronic equipment from lightning?
Thanks!

The GFCI is for protection of people, not equipment. That's why you are supposed to put the little stickers on that says "no equipment ground".

Surge protectors are just what the name says, for surge protection. There is little to protect from a lightning strike. A surge protector might in some cases protect from lightning, but not a direct hit.

 

[__dan]

Hi,
I will be working on an old house that only has two prong outlets installed. As far as I know there is no equipment grounding conductor run to the outlet because of that (I have not opened it up yet). From what I understand, if I put a GFCI at the beginning of the circuit it will protect the equipment being served. Is this correct? And will the GFCI protect them from all fault current including ground fault? And will this protect a flat screen tv or a computer?
Would it be even better to add a surge protector as well? What exactly does a surge protector do? Protect electronic equipment from lightning?
Thanks!

If it's BX with 3" x 2" metal boxes, there may be some ground there, but opening it to repair could fail the box fill calculation, if they have more than one 14-2 cable in there. If it's working and conventional for the time it was installed, it may be better to not touch it and add new for new loads.

I would look at leaving the two prong circuits in place for light loads and two wire circuits, table lamps, cordless phones. Run new grounded circuits for anything sensitive and expensive, especially PC's and electronics that take a three prong cord. Run new dedicated circuits for heavy appliances, especially appliances that have grounded metal exteriors, washers, fridges, kitchen counter appliances.

The SPD's are all three prong cord devices, probably clamping line to neutral, and also line to ground. They will need a solid ground to function properly. Analog electronics like stereos will use the ground as a signal reference and ungrounded circuits may give you 60 cycle hum in the speakers. The GFI trips for leakage current in the milliamp range. It may detect and trip for ground fault current but it's not the same as a breaker tripping for fault current, different type of device. Grounding and bonding is a wire, the GFI is a different layer of protection.

Leave the 1950's wiring in place for the 1950's loads and run 2012 wiring for the 1987 loads.

 

[electro7]

Thanks for the feedback. Running a new grounded circuit will be the approach I take. So is it not true that putting a GFCI at the beginning of a two wire circuit and adding three prong outlets after that will suffice?

_dan, thanks for explaining a bit how the SPD's work. I did not realize that analog electronics use the ground as a signal reference. So, the SPD's protect from surges. That is surges in voltage, right? Where do the surges come from?

Thanks again.

 

[WIMaster]

I would install GFCIs on the circuits you can to protect people.

As others said I would run new circuits with a grounding conductor to the sensitive electronics circuits and use a SPD at the point of use for those devices.
I would also install a SPD at the main panel. It does not have to be on its' own circuit unless specified by the manufacturer.

The surges come from multiple sources, most come from disconnecting large loads from the line either in the line either utility or end user.
Some come from lightning or other sources.

 

[electro7]

Sweet, thanks for the insight!