Imposing a load while testing a receptacle

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hardworkingstiff

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Wilmington, NC
I do a lot of work around marinas. I was at one this week and the dock master had a couple of 50-amp 120/240-volt receptacles that he thought were having problems. I found the circuit breaker to one of them was defective on one leg, but could not find anything wrong with the other one.

This started me thinking, I need a tester that I can plug into this receptacle and impose a load (preferably incremental) and read the voltages at the load. I was thinking about how to build one, but then figured I'd ask here if anyone has ever seen anything that would meet my requirements?

I tried a search on the Internet, but either nothing is out there, or I don't know how to word the search.

Thanks in advance,
Lou
 
I made a primitive load bank out of 4 trashed 2000 watt base board heaters once. The down side was the space they took up, other than that they worked pretty good. I could add them one at a time to the load by individual switches.

If you can find some small resistive heaters like "in wall" types, you can make a smaller version.

Roger
 
Purchase a variac (variable transformer) and a unit heater slightly larger that the load you wish. Small load banks in this instance would most likely be more expensive than this setup. Another option would be to use several small unit heaters, so you could step load rather that rampp up the load. The biggest advantage of the unit heaters over the strip heater is size. If you go the variac route you will need to rewire the controls, powering the fan from the line side of the variac.

Cannon load banks are excellent for small load application often refered to as suit case load banks, they are more portable thn Simplex or Avtron load banks.

www.cannonloadbanks.com
 
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How about a couple of hair blow-dryers? They use more power in a small space (typ. 1875 watts) than just about anything else. Plus, you have an audible voltage indicator as you hear the motor change speed.
 
I agree you can certainly make something up.

However IMO it depends on the customer.

Some will not be impressed when you show up with a box of hair dryers even though they would work fine.

Besides if you show up with fancy test equipment you can charge for it's use.:smile:
 
I have an old Shuretest, made by Ideal now, that imposes a 15A load on circuits less than 150vac, while reading the line impedances, voltage, v-drop, etc. Mine cannot load 240 or 277vac lines, but still shows voltage, reversed lines, & open conductors with these voltages. It also has a built in GFCI test that requires a working EGC.

I doubt the new one's can load over 150vac either, but they retail for around $250.00. The new models now report available short-circuit amps, (ASCC) and some have a built in AFCI test routine that inspectors have used to generate lots of contractor appeals, which were ruled in favor of the contractors if memory serves.

I recently calibrated the 15A load test on my 20-year old Shuretest ST-1THD, and found the load value has deteriorated to 9A. Operators may ignore the 30 sec. cool off time between loads and damage the tester in very short order. With my 9A load test, I now rely on its line impedance values, still accurate, to derive V-drop=(Z * I) using any amperage I want.

These THD models measure harmonics and have provisions for a clamp, but No ASCC or AFCI feature. There are other hand held outlet testers like this, but the Shuretest is most popular, and perhaps most dangerous, --enforcement of external AFCI test results-- among the inspector community.
 
iwire said:
I agree you can certainly make something up.

However IMO it depends on the customer.

Some will not be impressed when you show up with a box of hair dryers even though they would work fine.

Besides if you show up with fancy test equipment you can charge for it's use.:smile:
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Well, that depends. In the computer biz we do something called "Customer Environment Testing" where we specify that systems have to be tested according to how customers are going to use them. I'd tell the customer that's what I'm doing.

Bring a bathrobe. Sing in the shower. Make it realistic :D
 
tallgirl said:
Bring a bathrobe. Sing in the shower. Make it realistic :D
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Reminds me of a story a fellow EC related to me... His helper on a large residential remodel job went missing for nearly 1/2 an hour. He reappeared from another part of the house in a fresh set of clothes and his hair was wet. Aparently, he had to leave early that day for a doctor's appointment, and used the homeowners shower to clean up before he left the jobsite. He was summarily fired.
 
tallgirl said:
Bring a bathrobe. Sing in the shower. Make it realistic :D
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No thanks, I am a professional, I don't show up to work looking like a moron.

The company I work for charges premium rates for testing services, we don't show up with cheap toys.
 
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