Hot Tub Motor Rating for Amperage

[DerbyDad03]

A friend is having trouble with a GFCI breaker tripping when he turns on the swtich for his whirlpool tub. It's not a "new" problem as it's been happening since he moved in 5 years ago.

(This is the GFCI breaker that I asked about yesterday when I wanted to know if you could tell what caused it to trip - a fault or overcurrent)

The main symptom is that when he first turns on the wall switch and the breaker trips. He goes to the basement, resets the breaker, flips the wall switch again and the tub powers up and runs fine. This is a consistent symptom. He hasn't run any tests to see how long between uses he has to let everything "rest" before the initial trip will occur, so that is an unknown.

Here are some more details and a few questions.

The circuit in question is a dedicated 115V circuit on a 20A breaker with what my friend believes is 10 gauge wire. I haven't looked at it, but he said that he has both 12 and 14 gauge wire at home and the wire to the tub is larger than both of them.

On the tub motor there is one label that gives the voltage and amperage specs:

230V / 115V 8A / 16A

There is a another label that says:

"This device must be used with a switch sufficient for a 1 1/2 HP motor. A 30 Amp electrical supply is required."

The wall switch is rated for 30A, but as noted earlier, the breaker is a 20A GFCI.

So here are my questions:

Is the 20A breaker the (obvious) problem?

If so, why does it trip once and then work?

If the motor is rated at 16A @ 115V, why is a 30A circuit required? If it's for startup surges, then isn't a 30A breaker too big for steady- state operation? It seems to me that a lot can go wrong between the

16A the motor draws under steady-state operation and the 30A required to trip the breaker.

Thanks!

[chaniarts]

i believe typically you don't want steady state to be higher than 80% of the breaker, or 16. perhaps they felt it would be too marginal and spec'ed the next one higher than 20a.

a 20a breaker will supply more than 20a for a very short period of time. a cold motor may require more than a warm moter. perhaps the first failure warms up, or breaks loose some crud in the motor so that it starts easier the next time, and when it sits, it hardens up again.

[gfretwell]

It sounds like he needs a 30a GFCI breaker. When they say "30" they are talking about what it takes to start the motor.

[DD_BobK]

Does the wall with merely provide power to the hot tub & the tub has its own on/off swtches?

If so......my suggestion. if you don't want to replace the 20A with a

30A until your;e sure.

Turn the breaker off, remove the wall switch from the circuit, wire nut the wires to "bypass" the switch.

Turn the breaker back on & see if it still trips.

I used to have small oscillating fan with a plastic housing & two prong plug. Switching speeds or turning the fan off would trip many of my GFI's (~

2008 units) but not all.

Perhaps the problem is the GFCI portion of the breaker is too sensitve?

How hard would it be to rework the circuit to have a regular breaker & a GFI at the switch box? (much more convenient to reset)

cheers Bob

[John Grabowski]

*The manufacturer requires a 30 amp circuit. Therefore you should have a 30 amp breaker. You could try giving them a call to hear their response. I would put an ammeter on the line to see what it is actually drawing. Is there a built-in heater on this tub?

[DerbyDad03]

I don't know about the heater. I'll have to ask the owner.

I'll get back to you.

[jamesgangnc]

Switch to a 30 amp after you make sure that the circuit has 10 guage wire on it. Start up current is more than the run current. The heater would explain why the manfacturer calls for a 30 amp circuiit. If the wire is 12 guage and the run is short you might be able to find a 25amp gfci and could get away with that.

[gfretwell]

If this is just the motor load, it still would not be unusual to have

30a O/C protection for a 16a motor. The code says that can be up to 250% of FLA. (40a) I don't want to make your head hurt but the code also says you could do this all on 14ga wire if this is only a motor load. That is a common question on the inspector test. It gets more complicated if this is a mixed motor and non-motor load. As long as he really has 10ga wire it is a slam dunk, put in the 30a breaker the installation instruction call for and the load doesn't matter. They may not have that breaker at the Home Depot but they are available.

[jamesgangnc]

Seems unlikely that a "hot" tub doesn't have a heater.

[bud--]

I agree with John and gfretwell.

I expect the 30A requirement is to start the motor. A motor can momentarily draw 6x the rated current when it starts. A 20A breaker can carry a momentary overload - this overload appears to trip it. Heaters, if any, add to the problem.

Motor circuits have different rules than ordinary branch circuits. Overload protection for the motor is commonly a "thermal protector" in the motor. (Also commonly a "motor starter" with overload protection.) The overload protection for the branch circuit is at the load end of the circuit. The breaker is for short circuit protection of the circuit. The rating of the breaker has to be large enough to start the motor. The breaker may, on some cases, be significantly larger than the rating of the wires.

Garden variety AC wall switches (not AC-DC) can be used for motor loads up to 80% of their amp rating (up to 2HP). The 30A switch complies and is not likely the problem.

If the manufacturer says a 30A circuit is required (which the manufacturer did) the NEC makes that an installation requirement. The

20A breaker is a code violation. (It is likely a lot cheaper than a 30A GFCI.)

The fix is likely to change the 20A breaker to a 30A GFCI that should have been installed in the first place.

[DerbyDad03]

True. My error. It's a whirlpool, no heater.

[DerbyDad03]

Thanks to all.

As long as we're chatting about code violations, my friend (co-worker) was trying to explain the mix of Black, Red, White and ground wires that he found in the switch box.

As we were talking on the phone and he was explaining what color was connected to what, it didn't make any sense to me. I'm fairly familiar with simple residential wiring but motors, 220, etc. are just a tad outside of my experience. Even given that, the wireing configuration that he was describing just didn't make sense. He said he would take some pictures and bring them work.

So I'm looking at the pictures of the switch box the next day and here's what I see:

The white wire from the source is nutted to the white wire to the tub. The black wire from the source is attached to the switch as is the black wire to the tub.

I'm fine with all that.

However, the Red wire from the source is nutted to the Red wire to the tub. That seemed wierd.

At first I thought that something at the tub was always "hot" and that maybe the switch just controlled the motor.

Then he showed me a picture of the breaker box and there it was, clear as day:

There was a lone Red wire attached to the grounding bar. He showed me a picture of the motor connections and there it was again: The Red wire was attached to the Green wire on the motor.

Whoever pulled the wires used the Red as the ground wire.

[Tony Hwang]

OH, my, sounds like the tub may be unsafe to use. Motor is usually rated by HP. Amperage depends on the efficiency of motor. Higher efficiency motor saves energy.

[John Grabowski]

Thanks to all.

As long as we're chatting about code violations, my friend (co-worker) was trying to explain the mix of Black, Red, White and ground wires that he found in the switch box.

As we were talking on the phone and he was explaining what color was connected to what, it didn't make any sense to me. I'm fairly familiar with simple residential wiring but motors, 220, etc. are just a tad outside of my experience. Even given that, the wireing configuration that he was describing just didn't make sense. He said he would take some pictures and bring them work.

So I'm looking at the pictures of the switch box the next day and here's what I see:

The white wire from the source is nutted to the white wire to the tub. The black wire from the source is attached to the switch as is the black wire to the tub.

I'm fine with all that.

However, the Red wire from the source is nutted to the Red wire to the tub. That seemed wierd.

At first I thought that something at the tub was always "hot" and that maybe the switch just controlled the motor.

Then he showed me a picture of the breaker box and there it was, clear as day:

There was a lone Red wire attached to the grounding bar. He showed me a picture of the motor connections and there it was again: The Red wire was attached to the Green wire on the motor.

Whoever pulled the wires used the Red as the ground wire.

*I have seen the red wire used a number of times as a ground not only in residential, but in commercial installations as well. A simple fix is to apply some green tape, however I am now questioning the entire installation because of these two serious violations (Breaker size and red ground).

How about posting those pictures?

[jamesgangnc]

I didn't think the code had hard rules about wire color. Some green tape on the ends would help the next guy to work on it.

[DerbyDad03]

I was shown hardcopies printed from his cell phone, so I don't have links. He'd have to send them to me or post them. I'll see what he says.

I had already told told him to mark the Reds with Green tape before he puts it back together.

The rest of that particular installation looks fine. It's really nothing more than a typical switched circuit in a 30 YO house, but with the wrong colored wires being used. My guess is that the contractor (or whomever) had some 10/3 wire lying around and was to lazy/cheap to go buy some 10/2 w/ground for this single installation.

I did see some other things in the panel box that caught my eye (ganged breakers, etc) that he doesn't know what they control. He says he has a stove receptacle that he doesn't use, so that might be one of them (Black to one breaker, White marked with Black tape to the other). His basement ceiling is finished so visually tracing wires is out.

I offered to stop over this weekend with my meter, etc. and see if we can't get his box lable correctly so he knows what he's got.

[bud--]

Green tape certainly would help.

No mention of ground wires. From Derby it sounds like Romex was used - any Romex available for a long time has had a ground wire.

As for the NEC, _in general_:

- ground wires #6 and smaller have be green or bare. They can be tape-marked at the ends if larger than #6.

- neutral wires #6 and smaller have to be white. Again, they can be tape marked at the ends if over #6.

It is not that hard to have (or get) green or white wire in sizes through #6.

The other magic color is orange. If there is a high-leg delta 3-phase system, orange is used for the high leg. Else it can be used for anything.

[DerbyDad03]

re: - "ground wires #6 and smaller have be green or bare. They can be tape-marked at the ends if larger than #6. "

By that, are you saying that using the Red from a 10/3 w/o ground length of romex as a ground wire is not permissible even if it is marked?

I just want make sure that I'm going in the right direction when you use "larger" and "smaller" in relation to the numbers.

(I know how the numbers work, I just want to make sure I understand what you are saying)

[gfretwell]

Strip all the visible red insulation off. (all the way back to the cable jacket)

[trader4]

Am I the only one here that thinks a 1 1/2hp, 16A motor requiring a

30A breaker for a mere whirpool tub in a bathroom is odd? Does it whirl the water across the house?