Grounding Tester

Old 02-24-03, 10:48 AM
Thread Starter
Join Date: Nov 2001
Location: usa
Posts: 558
Received 2 Upvotes on 2 Posts
Grounding Tester

In general how accurate are those yellow 3 prong testers. The ones with the two yellow lights & one red light. When just the two yellow lights go on supposedly your correctly grounded.
Old 02-24-03, 11:10 AM
Master Electrician
Join Date: Dec 2001
Location: Indiana
Posts: 296
Upvotes: 0
Received 0 Upvotes on 0 Posts
Accurate, Well sort of ya/no. Do I use one? Ya. Inspectors do as well.

Is there a ground when the light comes on, Sure. Is there a good ground ? Is the ground per code ? Is the ground going to hold under a short ? Answering these questions then no it's not accurate.
Old 02-24-03, 11:10 AM
fatkid66's Avatar
Join Date: Sep 2002
Location: Northeast NJ
Posts: 233
Upvotes: 0
Received 0 Upvotes on 0 Posts
id say if the tester is a good one and has UL listing it probably is accurate, but as they always say you have to first test the tester.
Old 02-24-03, 11:38 AM
Join Date: Sep 2000
Location: United States
Posts: 17,733
Upvotes: 0
Received 1 Upvote on 1 Post
These testers are incredibly simple, and thus perform reliably. It's just three simple voltage testers in one case. The three lamps are wired hot-to-neutral, hot-to-ground, and neutral-to-ground. In a properly functioning receptacle, the first two should light and the third should not light.

The biggest caveat comes when you have an open neutral. Because other loads may be present on the same circuit, the tester often incorrectly reads "hot/ground reverse" rather than correctly showing an "open neutral" reading. The hot/ground reverse indication occurs when both hot-to-ground and neutral-to-ground have voltage. The tester thinks that this means that the ground is hot. But it is really because both the hot and neutral are hot.

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: