Tanning bed tripping breaker on start-up

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Pat75

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Location
Maryland
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Electrician
I got a call to look at a problem for a tanning bed intermittantly tripping its breaker on start up.
Its a commercial 3 phase bed, wired by the installer to run on 240v single phase. They installed a buck boost and the measured voltage is 238v on the secondary. Data sheet shows it 50 amps. Measured current is 61 amps.
I called the supplier/installer and was told that current is perfectly normal when wired like it is.
All of this is wired with #4 cu on a 70 amp QO breaker. The intermittent trip occurs when the
"Start" is pushed on the bed.
The installer is saying the breaker must be bad. I think the breaker needs to be larger.
Again its intermittent, ONLY on startup, not once its running. I'll attempt to post pics but it says file too large.
Anyone run in to this before?
 
Pat75 said:
I got a call to look at a problem for a tanning bed intermittantly tripping its breaker on start up.
Its a commercial 3 phase bed, wired by the installer to run on 240v single phase. They installed a buck boost and the measured voltage is 238v on the secondary. Data sheet shows it 50 amps. Measured current is 61 amps.
I called the supplier/installer and was told that current is perfectly normal when wired like it is.
All of this is wired with #4 cu on a 70 amp QO breaker. The intermittent trip occurs when the
"Start" is pushed on the bed.
The installer is saying the breaker must be bad. I think the breaker needs to be larger.
Again its intermittent, ONLY on startup, not once its running. I'll attempt to post pics but it says file too large.
Anyone run in to this before?
Click to expand...
Did you meter the start up amp draw?
 
Here are pics.
Will check start up today.
 

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I ran that same concern by the supplier/installer.
They told me the voltage was perfect.
Has anyone else seen a high inrush on these beds?
 
Yes, that pretty much coincides with what I see as well. The supplier/installer missed the mark on this one.
Its on #4 thwn, 70 a breaker.
Wire size and breaker need to be upgraded.
 
ptonsparky said:
Label says 220 volt. Reduce the voltage further.
Click to expand...
I agree. I'm surprised the the manufacture is ok with running these 20 volts over their rated voltage and not at 208, 12 volts under the rated voltage. The higher voltage results in more heat and current.
 
If they are using switch mode electronic ballasts for the fluorescent lamps, the line voltage is likely not that relevant as most are auto-ranging now. But the initial current can be really high on those as the capacitors charge, if only for a fraction of a second. The NEMA standard is that the inrush must be less than 24x the steady state current (IIRC), and it's possible that being German, these are not designed even to those NEMA standards, so it could be even higher! That sort of issue depends on a lot of other factors, so it can appear random.
 
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