Hot Tub Calculation

[JohnDS]

Hey guys. I have a 240v Hot Tub to wire and the name plate says:

Max Current Draw: 48amps

I just want to double check and make sure I am sizing the wire properly.

48amp x 1.25 = 60amp

I am going to use a 60a breaker with #4 wires but I'm a little confused because after the 125% rule above, the calculation lands right on the size breaker I am using. Should I go to the next size up or should I use a 60amp breaker with #4 wire?

 

[infinity]

Why not a 50 amp circuit?

 

[Dennis Alwon]

Not sure you need to use 125%. In all my years I don't believe I have ever seen a 60 amp GFCI. Almost all tubs are 50 amp.

 

[infinity]

I wouldn't call a 48 amp hot tub a continuous load so no 125% is needed.

 

[JohnDS]

I wouldn't call a 48 amp hot tub a continuous load so no 125% is needed.

well it was either the 125% rule or the 80% rule for it being a motor correct?

80% of a 50amp breaker is 40amp...so doesn't 48 amps exceed this?

 

[Dennis Alwon]

well it was either the 125% rule or the 80% rule for it being a motor correct?

80% of a 50amp breaker is 40amp...so doesn't 48 amps exceed this?

I think you are confusing things. Usually the manufacturer will dictate what size circuit is required. Sometimes their numbers have the 125% built in already. Read the info.

Be careful some of these tubs require a full size EGC per manufacturers instruction.

 

[JohnDS]

I think you are confusing things. Usually the manufacturer will dictate what size circuit is required. Sometimes their numbers have the 125% built in already. Read the info.

Be careful some of these tubs require a full size EGC per manufacturers instruction.

it does not specify whether what size circuit or the 125%? What should I do? all it says is "max current draw: 48amps"

 

[Little Bill]

it does not specify whether what size circuit or the 125%? What should I do? all it says is "max current draw: 48amps"

The nameplate is telling you the max current draw, so a 50A would be good. As the others have said 50A is generally what is used, 50A GFCI that is. Usually the nameplate has already calculated everything and you can go by that, but double check the paperwork especially for the EGC size.

 

[JohnDS]

Ii

The nameplate is telling you the max current draw, so a 50A would be good. As the others have said 50A is generally what is used, 50A GFCI that is. Usually the nameplate has already calculated everything and you can go by that, but double check the paperwork especially for the EGC size.

Ok thanks guys. So in general, when it says "max current draw" the 125% is already in there?

 

[Dennis Alwon]

Ii

Ok thanks guys. So in general, when it says "max current draw" the 125% is already in there?

The problem is that the unit may not be considered a continuous load. You have motor load as well as heater loads in one unit. I doubt that generally speaking the unit will be on for 3 hours or more esp. once it heats up. Usually the info that comes with the unit will tell you what size breaker. Doesn't the nameplate tell you anything more than max amp?

 

[JohnDS]

The problem is that the unit may not be considered a continuous load. You have motor load as well as heater loads in one unit. I doubt that generally speaking the unit will be on for 3 hours or more esp. once it heats up. Usually the info that comes with the unit will tell you what size breaker. Doesn't the nameplate tell you anything more than max amp?

No it really doesn't, its an old hot tub, no paperwork.

 

[infinity]

You need to remember that the definition of a continuous load (125% factor) requires that the load operates at it's maximum current for 3 hours or more. That means, in this case, that the tub would need to have everything, all pumps, lights, heaters, etc. running continuously for 3 or more hours.

 

[Dennis Alwon]

No it really doesn't, its an old hot tub, no paperwork.

I really think it is a dp 50. I seem to remember checking for a dp 60 GFCI and I am not sure they even make them.

 

[JohnDS]

I really think it is a dp 50. I seem to remember checking for a dp 60 GFCI and I am not sure they even make them.

I see at depot, there is a 60amp gfci breaker with panel for $69. I think I might go with that just to be safe since there is no paper work.

That being said, is #4 THHN overkill, or should I use #6? It will be in pvc about 75'. I just want everything to be safe, but do not want to oversize the wire for the 60amp breaker. I know generally we use #6 for 50amp, that's why I was thinking using #4 for the 60amp. What do you think guys, #4 or#6 for 60amp gfci?

 

[Dennis Alwon]

If it is in PVC then #6 is probably good for 65 amps. I think I would run the #6 and install a 50 amp gfci but that's me. Can you look up the model of the tub on the internet. Oversizing the breaker could be a mistake.

 

[JohnDS]

If it is in PVC then #6 is probably good for 65 amps. I think I would run the #6 and install a 50 amp gfci but that's me. Can you look up the model of the tub on the internet. Oversizing the breaker could be a mistake.

I don't know the model because I was just focused on the nameplate at the time, but what do you mean by "oversizing the breaker could be a mistake". Do you mean as far as spending extra money when i don't have to or a safety mistake? If safety, please explain.

 

[tryinghard]

I don't know the model because I was just focused on the nameplate at the time, but what do you mean by "oversizing the breaker could be a mistake". Do you mean as far as spending extra money when i don't have to or a safety mistake? If safety, please explain.

I believe he means this because the breaker is the overcurrent protection device, if you go too large the protection will be set too high.

 

[JohnDS]

I believe he means this because the breaker is the overcurrent protection device, if you go too large the protection will be set too high.

Maybe I'll install a regular 50amp breaker at the main panel, and install a 60a gfi breaker out by the hot tub. This way it covers both safety and future cost in the case where the 50 was not enough. Right now the difference in price between the 50 gfi & 60 gfi hot tub panel is $20. So I'm thinking that if worse case the circuit became inadequate, all I have to do is replace the regular 50 at the main panel with a regular 60 for $12 or so. The wire will already be #6 ready to go.

Now, I forgot if this hot tub even accepts a neutral connection, but in the case that it doesnt, I believe you guys said a while back to just hook up the gfi regularly, but just hook up the two hots from gfi to hot tub with egc and it will still gfci protect the tub with no neutral, correct?

 

[Dennis Alwon]

Maybe I'll install a regular 50amp breaker at the main panel, and install a 60a gfi breaker out by the hot tub.

That is a good idea.

Now, I forgot if this hot tub even accepts a neutral connection, but in the case that it doesnt, I believe you guys said a while back to just hook up the gfi regularly, but just hook up the two hots from gfi to hot tub with egc and it will still gfci protect the tub with no neutral, correct?

That is correct

 

[JohnDS]

I believe he means this because the breaker is the overcurrent protection device, if you go too large the protection will be set too high.

That is a good idea.



That is correct

Ok it sounds like a plan. One more thing, are the normal THHN wires we buy considered compact or regular because I noticed that there are two different tables for conduit fill for ENT. One table for "conductors or fixture wires" and the other for "compact conductors". And I've also noticed the #8 has no specs on one of the tables for some reason.