Questions about tripping breakers and Tanning beds.

[cal.interiors]

Im trying to figure out what the heck is going on at my wifes tanning. All the beds have disconnects in the room and in one room in particular, the breaker keeps tripping and I'm trying to figure out what the heck is going on. Heres some better details:

*In the room is square D breaker 80a
#6 thhn running from dis connect to main panel to another 80a breaker
Bed will run full cycle(7 minutes) and usually trip towards end or if I reset and try and run again

So I hooked up a clamp meter to the lines at the bed from the disconnect and it was like 62a running. Then i checked line between disconnect and main panel and like 100a??? What the heck is that.

So now im really confused. I was hoping for just a bad breaker but now im lost. Can anyone give me some insight here.

 

[cal.interiors]

Sorry, meant #4 thhn.

 

[growler]

#6 thhn running from dis connect to main panel to another 80a breaker

Who thought it was alright to protect #6 thhn with an 80 amp breaker?


Go back to the installation instructions for the bed and see how much current the bed should draw. The manufacurer will give a breaker size for the bed.

A tanning bed is nothing more than a huge light fixture. There are a ton of ballast in the bed.
From the beds that I have hooked up many come from the factory with defects.

You need to get an electrician that's familair with these to trouble-shoot or provide more on the specification of these beds. All tanning beds are not created equal.

 

[cal.interiors]

Who thought it was alright to protect #6 thhn with an 80 amp breaker?


Go back to the installation instructions for the bed and see how much current the bed should draw. The manufacurer will give a breaker size for the bed.

A tanning bed is nothing more than a huge light fixture. There are a ton of ballast in the bed.
From the beds that I have hooked up many come from the factory with defects.

You need to get an electrician that's familair with these to trouble-shoot or provide more on the specification of these beds. All tanning beds are not created equal.

I reposted #4 thhn above not #6
Im actually pretty good with the beds as I do most of the basic repairs on the bed. I was thinking maybe bad capacitors as that could raise current draw but why would the draw be correct on the bed to disconnect side and way high after from disconnect to main panel.

 

[growler]

Im actually pretty good with the beds as I do most of the basic repairs on the bed. I was thinking maybe bad capacitors as that could raise current draw but why would the draw be correct on the bed to disconnect side and way high after from disconnect to main panel.

Unless you had a ammeter on both at the same time the current draw may have changed between the time you checked at the bed and the feed to the disconnect.

 

[growler]

why would the draw be correct on the bed to disconnect side and way high after from disconnect to main panel.

Make sure this is really happening because the current has to go some place and the only place it could go is a short to ground ( that's if you are measuring corectly). Check out the disconnect and see if it's melted inside. What size is the disconnect?

 

[GoldDigger]

Or the disconnect is miswired?
Example:
Suppose bed wants 120/240 three wire input and both L1 and L2 leads of the bed are connected to the same phase inside the disconnect.
The result would be twice the expected L1 and N current.
Similar possibilities with different numbers for a 3 phase wye circuit.

Tapatalk!

 

[cal.interiors]

No the disconnect is wired correctly. This is a single phase btw. This bed and setup have been running fine the last 3 years no problems until I replaced all the bulbs last week but I dont see how that would even be connected.

The dis connect is not melted at all. There is also a buck booster transformer hooked up from disconnect to the bed that raises the voltage as bed needs min 220 up to 230v but I checked that and all seems ok. Voltage is 225ish

It just doesnt add up. Why would the draw be that high with no other effects. I even measured other beds lines running to make sure my ammeter is somewhat accurate and everything else measured out fine.

 

[GoldDigger]

Possibly a high current draw in the buck transformer itself if you measured current on the two sides of it?
High idling current could increase the primary side current but at a low power factor without the transformer getting too hot..
You did not mention that there was another component (the buck transformer) between the disconnect and the bed!

Tapatalk!

 

[growler]

There is also a buck booster transformer hooked up from disconnect to the bed that raises the voltage as bed needs min 220 up to 230v but I checked that and all seems ok. Voltage is 225ish

OH, what's the feed voltage. I would assume that it's around 208.

225V X 60 amps = 13500 W
13500W/208 = 65 amps

But if the input voltage is low this would change everything. Anyway the current draw on the feed should be somewhat higher because the voltage is lower.

 

[kwired]

No the disconnect is wired correctly. This is a single phase btw. This bed and setup have been running fine the last 3 years no problems until I replaced all the bulbs last week but I dont see how that would even be connected.

Make sure you didn't replace with the wrong lamps. There are differences and they will still fit in the same lampholder.

 

[growler]

So I hooked up a clamp meter to the lines at the bed from the disconnect and it was like 62a running. Then i checked line between disconnect and main panel and like 100a??? What the heck is that.

So now im really confused. I was hoping for just a bad breaker but now im lost. Can anyone give me some insight here.

Possibly a high current draw in the buck transformer itself if you measured current on the two sides of it?

I'm thinking we whouldn't have a 100 amp on line side and 62 on the load side but he does need to check right at the transformer. May be bad.

 

[cal.interiors]

OH, what's the feed voltage. I would assume that it's around 208.

225V X 60 amps = 13500 W
13500W/208 = 65 amps

But if the input voltage is low this would change everything. Anyway the current draw on the feed should be somewhat higher because the voltage is lower.

Yes 208 incoming. Actually its 3 phase into building and 3 phase panel but all beds are single phase on 2 pole breakers and are designed to run single.

 

[cal.interiors]

So I guess next thing is to check the transformer then huh?

I really appreciate the feedback guys!!!

 

[kwired]

Yes 208 incoming. Actually its 3 phase into building and 3 phase panel but all beds are single phase on 2 pole breakers and are designed to run single.

If you are boosting voltage then your supply side of the boost transformer will have higher current than the load side. To get the same kVA output at a higher voltage the current will go up on the lower voltage in proportion to the change of voltage.

V x A = VA

240 x 62 = 14880

208 x 71.5(ish) = 14880

That law can not be broken.

Is one of your measurements on supply side and other on load side of the boost transformer?

 

[charlie b]

Let me see if I understand the installation. There is a panel with an 80 amp breaker. This breaker connects to a #4 wire, which is connected at the other end to a disconnect switch. On the other side of the disconnect switch there are wires that lead to the tanning bed. You measured 62 amps on the load side of the disconnect and 100 amps on the line side of the disconnect, and you did the two measurements close enough (in time) to each other that you are confident that the load did not change while you moved the ammeter to the other location. Is this all correct?

If so, then you have a serious problem, and it is at or upstream of the disconnect. But perhaps there was enough time between the two measurements for the load to have changed. I would ask for clarification of this point, before going further.

In general, when a system that has worked well for a long time suddenly has a problem, then the first thing to ask is what happened recently. If you recently changed light bulbs, and if the symptom showed up shortly thereafter, then I would seriously look at the possibility that some aspect of that repair/replacement task is the cause of the problem. It might not be as simple as the wrong bulbs were installed. You might have bumped something, or disconnected (and forgot to reconnect) something, or failed to screw something back into place properly. But there is a high likelihood that your answer lies somewhere within that realm.

 

[growler]

You measured 62 amps on the load side of the disconnect and 100 amps on the line side of the disconnect, and you did the two measurements close enough (in time) to each other that you are confident that the load did not change while you moved the ammeter to the other location. Is this all correct?

Except for the fact that he left out the buck/boost transformer.

So it would be 62 amps at the bed ( load for transformer) or close to whatever would be expected ( seems to let the bed off the hook ) and 100 amp at the disconnect which should be the same as line voltage for the transformer.

 

[GoldDigger]

Except for the fact that he left out the buck/boost transformer.

So it would be 62 amps at the bed ( load for transformer) or close to whatever would be expected ( seems to let the bed off the hook ) and 100 amp at the disconnect which should be the same as line voltage for the transformer.

If we go with the nominal voltages of 208 at the service and 240 (not 220 or 230) at the bed, we would expect 62A at the bed to correspond to
62*240/208 = 71A at the supply side of the boost transformer, not counting any additional inductive current that might be flowing in the primary of the boost transformer.
Not close enough to 100A to satisfy me, so I would definitely look for a problem in the transformer.
Possibly even including a partial short to ground if this is not a GFCI circuit?

 

[growler]

If we go with the nominal voltages of 208 at the service and 240 (not 220 or 230) at the bed, we would expect 62A at the bed to correspond to
62*240/208 = 71A at the supply side of the boost transformer, not counting any additional inductive current that might be flowing in the primary of the boost transformer.
Not close enough to 100A to satisfy me, so I would definitely look for a problem in the transformer.
Possibly even including a partial short to ground if this is not a GFCI circuit?

Sure and at anyplace close to 100 amps it wouldn't take long to trip an 80 amp breaker.

In a tanning salon there is usually a panel packed full of breakers operating at close to capacity and producing lots of heat.

When they install the new buck/boost they need to make sure it's bugged-up right so the connections don't come loose because of vibration ( termminals or split bolts ).

 

[cal.interiors]

Well I guess I should go check the transformer and all the connections. I still dont understand how the line side could be reading so much higher though. The buck booster is wired: Whip from bed to booster, booster to disconnect, disconnect to main panel. Why am I getting that reading above disconnect? Boy this gets confusing......


Im going down their now and will check everything and get a few more readings and report back.