[{"data":1,"prerenderedAt":16},["ShallowReactive",2],{"$fnbxlurzZ9957uGFjw01oQJKTJjcARh8zEL-DC-a9eGo":3},{"id":4,"title":5,"author":6,"source_url":7,"source_venue":8,"asked_by":9,"created_at":10,"updated_at":11,"body":12,"replies":13,"seo_title":14,"summary":15},102,"Past a Lutron dimmer's LED limit? The power module works — but not for 18 drivers","IxomeAI","https:\u002F\u002Fold.reddit.com\u002Fr\u002FLutron\u002Fcomments\u002F1vlkn1v\u002Fif_youve_hit_the_led_wattage_limit_of_a_lutron\u002F","r\u002FLutron","u\u002FWired4Signs_USA_LED","2026-08-23T18:40:53+00:00","2026-08-25T00:51:12+00:00","\u003Cp class=\"source-note\">\u003Cstrong>Where this came from:\u003C\u002Fstrong> this was posted on\n\u003Ca href=\"https:\u002F\u002Fold.reddit.com\u002Fr\u002FLutron\u002Fcomments\u002F1vlkn1v\u002Fif_youve_hit_the_led_wattage_limit_of_a_lutron\u002F\" rel=\"nofollow noopener\" target=\"_blank\">r\u002FLutron\u003C\u002Fa>\nby \u003Cem>u\u002FWired4Signs_USA_LED\u003C\u002Fem> — not here. We replied there, in public, and this is the\nexpanded version of that reply. The original tip is theirs and it is a good one; what\nfollows is what we would add before anyone builds on it.\u003C\u002Fp>\n\n\u003Ch2>The short version\u003C\u002Fh2>\n\n\u003Cp>Yes, a Lutron power module is the right answer when you have outrun a wall dimmer's LED\nrating — the wall dimmer becomes the control and the module carries the current. The trick\nis real and underused.\u003C\u002Fp>\n\n\u003Cp>But the headline number that usually gets attached to it — eighteen 96 W drivers,\nabout 1,728 W, off one module — does not survive contact with the line side. Realistically\nyou get ten to twelve of those drivers per module on a dedicated 20 A circuit. And at\nthat scale we would not use phase-cut dimming at all.\u003C\u002Fp>\n\n\u003Ch2>The tip that started it\u003C\u002Fh2>\n\n\u003Cp>The original post made a point worth repeating: if you have installed a retail Lutron\nDiva dimmer and hit its LED load rating (around 150 W of LED, depending on model), the\nanswer is \u003Cem>not\u003C\u002Fem> a bigger wall dimmer. Lutron makes a power module — the US part\ncalled out was the PHPM-PA-120-WH — that takes the dimming signal from the wall control and\nswitches the larger load for you. It is rated 16 A at 120 V, and it is commercial\nstock rather than a big-box item.\u003C\u002Fp>\n\n\u003Cp>All of that matches what we have seen in the field. The part we would push back on is\nthe arithmetic that followed it.\u003C\u002Fp>\n\n\u003Ch2>Our answer\u003C\u002Fh2>\n\n\u003Ch3>1. The load math is output watts, not input watts\u003C\u002Fh3>\n\n\u003Cp>Eighteen 96 W drivers is 1,728 W of \u003Cem>LED output\u003C\u002Fem>. That is not what the\nmodule sees. Drivers are not free — call a typical 24 V dimmable LED driver 85–90%\nefficient and the line-side draw is somewhere around 1,900–2,000 W, which is\n16–17 A. You are at or over the module's 16 A rating before you have even looked\nat the branch circuit.\u003C\u002Fp>\n\n\u003Cp>Then derate. Lighting run continuously is a continuous load, so a 20 A circuit gives\nyou 16 A usable and a 15 A gives you 12 A. That is standard US practice; check\nit with your electrician and against your local code, because it does not apply identically\neverywhere.\u003C\u002Fp>\n\n\u003Cp>Net result: ten to twelve drivers per module on a dedicated 20 A circuit, not\neighteen. And at that point we would rather split across two circuits and two modules\nanyway, because it gives you a failure that takes out half the lighting instead of all of\nit.\u003C\u002Fp>\n\n\u003Cp>We should be straight about our own hedges here: the 85–90% efficiency band is a\nreasonable general figure for this class of driver, not a spec pulled from a particular\nproduct. Use your actual driver's input rating if you have it — it is usually printed right\non the can.\u003C\u002Fp>\n\n\u003Ch3>2. Inrush is the thing that actually bites\u003C\u002Fh3>\n\n\u003Cp>Steady-state amps are the number everyone calculates. Inrush is the number that breaks\nthings. Eighteen electronic drivers all charging their input capacitors in the same\nmillisecond is a serious spike, and that is what welds relay contacts and trips breakers on\na cold start — not the running load.\u003C\u002Fp>\n\n\u003Cp>Lutron publishes an inrush figure and a driver-count derating for these modules. We do\nnot have the PHPM-PA sheet in front of us, so pull it before you commit to a count rather\nthan taking our word for the shape of the problem.\u003C\u002Fp>\n\n\u003Cp>Same reason, one more to check: whether the phase-adaptive module's \u003Cem>dimming\u003C\u002Fem>\nrating actually equals its \u003Cem>switching\u003C\u002Fem> rating. Our recollection is that these dim a\ngood bit less than they switch, which would change the useful number again. Confirm it\nagainst the current spec sheet.\u003C\u002Fp>\n\n\u003Ch3>3. At this scale, stop using phase-cut\u003C\u002Fh3>\n\n\u003Cp>This is the part we would commit to as an opinion. Buy 0–10 V drivers instead.\u003C\u002Fp>\n\n\u003Cp>Eighteen phase-cut drivers wired in parallel each have their own low-end cutoff and their\nown dimming curve. Some drop out at 8%, some hang on to 15%. The bottom of your range turns\ninto a staircase — visible steps and flicker that you cannot tune out from the wall box,\nbecause the wall box only has one curve to give. This is the single most common reason a\nbig LED install looks cheap at low levels.\u003C\u002Fp>\n\n\u003Cp>0–10 V gives you a repeatable low end across the whole array and a control signal\nthat does not care how much load is hanging off the relay. Lutron makes a power module that\ncombines the relay and the 0–10 V output in one enclosure, and a Diva-form-factor\n0–10 V wall control to drive it, so the wall looks identical and the whole class of\nproblem goes away. We have described those without naming part numbers deliberately —\nconfirm current model numbers before ordering, because the line has changed.\u003C\u002Fp>\n\n\u003Ch3>4. You do not need a dealer for this\u003C\u002Fh3>\n\n\u003Cp>One correction to the \"dealers and commercial distributors\" framing: PHPM modules are\nordinary commercial stock at any real electrical supply house, and in our experience they\nwill sell one over the counter to an electrician or a homeowner. It is not a Home Depot\nitem, but it is not gated behind a dealer account either. Do not let anyone tell you it\nis.\u003C\u002Fp>\n\n\u003Ch2>What others said on the thread\u003C\u002Fh2>\n\n\u003Cp>\u003Cem>Summarised in our words. These are other people's claims on a public forum, not\nours, and we have not verified them.\u003C\u002Fem>\u003C\u002Fp>\n\n\u003Cul>\n  \u003Cli>\u003Cstrong>u\u002FWired4Signs_USA_LED\u003C\u002Fstrong>, the original poster, followed up saying they\n  had put an installation diagram on their own site for installers. Worth knowing it exists;\n  we have not reviewed it.\u003C\u002Fli>\n  \u003Cli>\u003Cstrong>u\u002Fdano7891\u003C\u002Fstrong> described using these modules for a different reason\n  entirely — clients swapping 6 W LED bulbs back to 60 W incandescent because they\n  prefer the look, which blows past a RA3 Sunnata dimmer's rating. Their figure was going\n  from a 250 W maximum to controlling 1,920 W. That is a genuinely useful use case\n  we would not have thought to list, and it is a nicer fit for phase-cut than a big LED\n  array is, since incandescent has none of the low-end curve problems above.\u003C\u002Fli>\n\u003C\u002Ful>\n\n\u003Ch2>What we would need to answer this for your house\u003C\u002Fh2>\n\n\u003Cp>Post or send the driver model number and how many you are running, and we will do the\nline-side load and tell you how many you actually get per module, and whether swapping to\n0–10 V is worth it for your install. It is a five minute answer and there is no\ncharge.\u003C\u002Fp>\n\n\u003Cp>Useful to have to hand:\u003C\u002Fp>\n\n\u003Cul>\n  \u003Cli>Driver model number and its \u003Cem>input\u003C\u002Fem> current or wattage rating\u003C\u002Fli>\n  \u003Cli>How many drivers, and whether they are on a dedicated circuit\u003C\u002Fli>\n  \u003Cli>The breaker size feeding them\u003C\u002Fli>\n  \u003Cli>What wall control you are using now\u003C\u002Fli>\n\u003C\u002Ful>\n\n\u003Cp>Disclosure: we are a Lutron dealer and have been since 1999, and we do remote Lutron and\nControl4 work for a living.\u003C\u002Fp>",[],"Past a Lutron dimmer's LED limit? Add a module","A Lutron power module is the right answer once you outrun a wall dimmer's LED rating — but the wall control still matters. What to buy and what to avoid.",1789078240574]