Run time metering hookup for 240v 5hp motor

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Fred B

Fred B

Senior Member
Location
Upstate, NY
Occupation
Electrician
Customer wants me to hookup a runtime meter for his large shop equipment for him to schedule maintenance on the equipment, Mfg has maintenance at set periods. I'm not familiar with retrofitting such a device. Equipment in question is a 240V single phase 5hp motor with only 2 ungrounded conductor and a ground and doesn't have from factory any meter. Question is, the run meter that they have has no instructions, no identifiers other than a + and - near the spade terminal, would I be correct in that I really have no way from the markings to know 1. AC or DC, 2. Max voltage, 3. Amperage limitation, 4. No UL listing stamp, and just a made in China stamp (not necessarily relevant just side bar, another Amazon special) that I should advise that unit may be or is not usable for this application and what code reference could be used to substantiate such a claim? (If any) ps they were not able to get me any usable spec sheets for unit from the Amazon site.
 
We normally used Hobbs brand.
They were the industrial standard - 30 years ago, anyway!

ETA - if the one you have has + / - markings on the terminals, it’s likely DC and probably 12 volts. Common on engine-driven equipment.
 
A meter from a reputable supplier with proper certs and a data sheet available will cost $30.

Cheaper then your time testing an unknown meter.

On the other hand the Amazon meter will probably work just fine; I have one installed across the legs of the 120V motor on my home oil furnace and it has been working fine for a couple of years now. Just have the customer print out the original order and look at the item description and see what the seller says the supply voltage range is.

Jon
 
5 HP motor on single phase must have a motor starter or a vfd. You should be able to connect an hour meter to the start stop circuit and stay away from the motor conductors. If it's not UL listed don't use it
 
Eddie702 said:
5 HP motor on single phase must have a motor starter or a vfd. You should be able to connect an hour meter to the start stop circuit and stay away from the motor conductors. If it's not UL listed don't use it
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That's what I was thinking, but no neutral, and if meter is AC, and was to use it, my concern would be the only " - " connection would be ground and that could produce a negative impact or add to transient voltage on ground. Not sure how much draw is caused by the meter, but that would be returned on ground. (I believe is code violation.) Even bigger issue as motor is on a subpanel. Or am I way off base?
 
Fred B said:
Any codes to refer to for customer to support not using his product such as maybe "not listed"?
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"Unable to hook it up correctly, due to lack of instructions or clear markings" seems like it should be adequate. I wouldn't even bother with "not listed", since it's a weak appeal to authority. The National Electrical Code probably isn't going to be much help, as its scope is limited to preventing unsafe installations, not guaranteeing that everything will work correctly.
 
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