Max 50amp load ok on 6gauge wire for Hydroshark?

[rlme36]

Hi,

I have 6 gauge wire already in the wall and the hydroshark unit that I want to purchase is an SH3-12 with a max draw of 50amps and they recommend a 70amp breaker.

Is this still safe and compliant or do I need to upgrade the wire?

Thanks,

rob

 

[lametec]

Unless the unit falls under a category for which you can derate the cable requirements, 6 gauge will not be good enough.

For 70a you're looking at 3 gauge.

 

[Boiler]

I have a chart on my wall that has suggested gauge vs. breaker amps that has NAHI (national asociation of home inspectors) on it. It has 70 amp breakers with 4 ga wire. No clue what other sources say, this is just my chart. If I'm wrong, I'm not suprised.

 

[Charles (in GA)]

Electric heating is considered a continuous load, as such you cannot exceed 80% of the rated capacity of the circuits components. This unit is 12,000 watts, 240 volts, which is exactly 50 amps. Multiply 50 by 1.25 and you find that you need a circuit capable of at least 62.5 amps, which means using a 70 amp breaker, as you cannot step down to a 60.

Since your breaker and most other components in the circuit will be rated at 75C and no more, you have to use that table for the wire capacity. Looking at NEC table 310.16 we see that in the 75C column, copper, that basically every wire type (except TW and UF) in #6 AWG are rated at 65 amps, so, depending on what type of wire you have installed, you could possibly use the #6 you have, and if I recall, the code somewhere (and I'm too lazy to look this evening) says that you are allowed to step up the breaker to the next available size above the wire rating. That I know of, 65 is not a common size for a circuit breaker.

I'm sure one of our 'lectrical engineers will chime in on this if I'm all wet.

Charles

 

[rlme36]

Electric heating is considered a continuous load, as such you cannot exceed 80% of the rated capacity of the circuits components. This unit is 12,000 watts, 240 volts, which is exactly 50 amps. Multiply 50 by 1.25 and you find that you need a circuit capable of at least 62.5 amps, which means using a 70 amp breaker, as you cannot step down to a 60.

Since your breaker and most other components in the circuit will be rated at 75C and no more, you have to use that table for the wire capacity. Looking at NEC table 310.16 we see that in the 75C column, copper, that basically every wire type (except TW and UF) in #6 AWG are rated at 65 amps, so, depending on what type of wire you have installed, you could possibly use the #6 you have, and if I recall, the code somewhere (and I'm too lazy to look this evening) says that you are allowed to step up the breaker to the next available size above the wire rating. That I know of, 65 is not a common size for a circuit breaker.

I'm sure one of our 'lectrical engineers will chime in on this if I'm all wet.

Charles

Well, I guess I'll start looking for a 65amp square d breaker, assuming its the correct set up.

thanks,

rob

 

[Aceman]

What kind of #6 wire is it? Romex, MC cable, THHN in conduit??

 

[rlme36]

What kind of #6 wire is it? Romex, MC cable, THHN in conduit??

The wire is the romex type.

 

[Aceman]

I'd say it's too small then. #6 Romex is only rated for 55 amps. Like Charles said, you need wire capable of 62.5 amps. That means #4 Romex or #3 AL at a minimum. You'll need to make sure that unit accepts aluminum wiring as well if you go that route.

 

[Norcal]

Well, I guess I'll start looking for a 65amp square d breaker, assuming its the correct set up.

thanks,

rob

Your not going to find a 65 ampere rated breaker as it is not a standard rating.

 

[rlme36]

so here is whats interesting. The mfg of hydro shark is Stiebel Eltron and their tech literature recommends the below info. So I guess the question I have now is do I follow their advice or have my electrician come back and up the wire to 4ga as recommended.
The 70amp breaker is recommended by the reseller of the unit who rebadges it Hydro Shark, but the unit is clearly made by Stiebel Eltron.

9 Technical Data
Phase 1
Voltage V 240
Wattage kW 12
Max. amp, load A 50
Min. required circuit breaker size A 60
Required wire size AWG COPPER 6
Inlet temperature, max. °F (°C) 131 (55)
Water flow to activate unit GPM (l/min) 0.37 (1.4)
Nominal water volume GAL (l) 0.13 (0.5)
Working pressure, max. PSI (bar) 145 (10)
Tested to pressure PSI (bar) 290 (20)
Weight lbs. (kg) 13.2 (6.1)

 

[Aceman]

so here is whats interesting. The mfg of hydro shark is Stiebel Eltron and their tech literature recommends the below info. So I guess the question I have now is do I follow their advice or have my electrician come back and up the wire to 4ga as recommended.
The 70amp breaker is recommended by the reseller of the unit who rebadges it Hydro Shark, but the unit is clearly made by Stiebel Eltron.

9 Technical Data
Phase 1
Voltage V 240
Wattage kW 12
Max. amp, load A 50
Min. required circuit breaker size A 60
Required wire size AWG COPPER 6
Inlet temperature, max. °F (°C) 131 (55)
Water flow to activate unit GPM (l/min) 0.37 (1.4)
Nominal water volume GAL (l) 0.13 (0.5)
Working pressure, max. PSI (bar) 145 (10)
Tested to pressure PSI (bar) 290 (20)
Weight lbs. (kg) 13.2 (6.1)

If it was THHN or MC cable, #6 would be fine. Romex has a lower rating.....

 

[rlme36]

Ok, so the only recourse then is to upgrade to the 4ga romex as if I am not mistaken THHN needs to be protected and since my walls are still open, it will be an easy enough fix. Although I am afraid to see how much 4 ga romex is for roughly 35ft.

 

[Charles (in GA)]

Voltage V 240
Wattage kW 12
Max. amp, load A 50
Min. required circuit breaker size A 60
Required wire size AWG COPPER 6

NEC 424.72 for resistance type immersion heating elements....

NEC 424.82 for electrode type boilers.........

apply and have special requirements and provisions.

I do not know which the Hydro Shark is, but the resistance type immersion elements..... and not contained in an ASME rated/stamped vessel... have a restriction in the code that limits them to a max of 48 amps per heating element, and that those elements be protected at not more than 60 amps. You can have more than one element and supply those elements from separate circuits (as shown in the Hydro Shark instructions).

If this is an electrode type boiler (which I don't think it is, though I'm not sure) then you have to size wire, like any heat device at 125% of its rating except that if it exceeds 50Kw you drop back to sizing the wires at 100% of rating provided the boiler is physically marked with the minimum wire size.

You need to look at the codes pretty closely on this. Lots of variables.

Charles

 

[rlme36]

NEC 424.72 for resistance type immersion heating elements....

NEC 424.82 for electrode type boilers.........

apply and have special requirements and provisions.

I do not know which the Hydro Shark is, but the resistance type immersion elements..... and not contained in an ASME rated/stamped vessel... have a restriction in the code that limits them to a max of 48 amps per heating element, and that those elements be protected at not more than 60 amps. You can have more than one element and supply those elements from separate circuits (as shown in the Hydro Shark instructions).

If this is an electrode type boiler (which I don't think it is, though I'm not sure) then you have to size wire, like any heat device at 125% of its rating except that if it exceeds 50Kw you drop back to sizing the wires at 100% of rating provided the boiler is physically marked with the minimum wire size.

You need to look at the codes pretty closely on this. Lots of variables.

Charles

Well after speaking with the company rep to get better info the hydro shark 12 is a single element that is designed like a small water heater in a cooper vessel. I assume that means its an immersion type heater. His thoughts after discussing the square footage (1000 sqft)was that I could also use the 10kw which only draws 40amps max. With this sceanrio my 6 gauge romex should be fine as this setup only needs a 50amp breaker. Does this sound about right?

rob

 

[Charles (in GA)]

Personally, I don't see how they get away with building something that exceeds the limits placed on it by the code. 48 amps is 48 amps, plain and simple, yet the unit clearly draws 50 amps.

1000 sq ft is not much and depending on your insulation, and since the 10Kw is not much of a decrease from the 12Kw, you could be OK. I'd talk with a professional installer or two to get a general consensus on it.

Charles