Is is safe to plug a surge protector into a 2-prong outlet using a 3-to-2-prong adapter?

Question

I live in an apartment that has essentially no 3-prong electrical outlets. I need to plug in a modest amount of computer equipment (which has a mix of 2- and 3-prong plugs), and I want to plug this equipment into surge protectors. Physically, I can accomplish this using cheap 3- to 2-prong adapters, but is that safe?

In part, my question is, what happens when a surge protector does its thing? One plausible scenario is that it dumps the excess energy into the ground conductor, which seems like it could pose a much worse problem than damaged equipment if that ground is poor or nonexistent.

This is in Colorado if that matters.

These questions seem related but don't directly answer the surge protector safety question:

• What to do with an apartment with only 2-pronged outlets
• How do I use three-prong appliances when my outlets are mostly two-prong?
• Is it unsafe if some three prong outlets don't properly test as grounded?

Answer 1

According to howstuffworks.com the most common type of surge protectors contain a metal oxide varistor or a gas discharge arrestor that utilizes the grounding wire to divert extra current.

However, as others have commented, the neutral wire is usually also used in conjunction with the ground, and therefore, you should get some, but not full protection when bypassing the 3rd prong.

That said, it's never considered safe to use bypass the 3rd prong (even with 2 to 3 prong adapters) and it is likely your insurance / the manufactures insurance will not cover damages caused as a result of such use.

Answer 2

The common 2 to 3 prong adapter has a screw tab, usually colored green. This is meant to go under the cover plate screw.

Why? There was a narrow period of time where a grounded wire was used, but outlets were still 2 prong. Thus it's possible the center screw on the outlet actually is grounded. If so the best thing is to install grounded plugs, but since you're renting, you can just use the 2 to 3 prong adapter.

Answer 3

A good option is a "whole house" surge protector, which is very easy to install (See a guide I wrote at http://guides.obviously.com/Whole-House-Surge-Protectors/1482 ).

It won't add a third prong to your plugs, but at modest cost for your landlord will protect his house (e.g. protect his sump pump, dishwasher, light bulbs, etc.). That's what you tell him. And it will protect your computers.

As for the point of use strips: it's true most will have three protection devices arranged in a triangle. But keep in mind neutral and ground are connected together at the panel anyway. From a surge point of view the 2-prong is not all that bad.

But point of use protection is not enough anyway, not in areas that actually have lightning. An "online" UPS can be a good substitute. But the best protection is to have both a whole house unit and point of use protection.

Note: you have very little to worry about with computer equipment and the third prong ground: I rip the 3rd prong off most laptop supplies for example, as I know it goes essentially nowhere.